Magnetic Shear Damped Polar Convective Fluid Instabilities Atul, Jyoti K.; Singh, Rameswar; Sarkar, Sanjib ...
Journal of geophysical research. Space physics,
January 2018, 2018-01-00, 20180101, Volume:
123, Issue:
1
Journal Article
Peer reviewed
Open access
The influence of the magnetic field shear is studied on the E × B (and/or gravitational) and the Current Convective Instabilities (CCI) occurring in the high‐latitude F layer ionosphere. It is shown ...that magnetic shear reduces the growth rate of these instabilities. The magnetic shear‐induced stabilization is more effective at the larger‐scale sizes (≥ tens of kilometers) while at the scintillation causing intermediate scale sizes (∼ a few kilometers), the growth rate remains largely unaffected. The eigenmode structure gets localized about a rational surface due to finite magnetic shear and has broken reflectional symmetry due to centroid shift of the mode by equilibrium parallel flow or current.
Key Points
Magnetic field shear effects on convective fluid plasma instability processes are investigated for high‐latitude F layer ionosphere
Gradient drift, gravitational, and current convective instabilities are found to be important
The magnetic shear‐induced stabilization is more effective at the larger‐scale sizes as compared to the scintillation causing intermediate scale sizes
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
A method for solving inverse quantum scattering problems on a half line is proposed. It is based on the application of the transmutation operators and recent results on series expansion of the ...integral transmutation kernels. From the corresponding Gel'fand-Levitan equation a system of linear algebraic equations is derived for the coefficients of the Fourier-Legendre series expansion of the output (transmutation operator) kernel. It is shown that the knowledge of the very first coefficient is sufficient for recovering the potential and hence for solving the inverse problem. A numerical illustration is presented.
Root detritusphere is one of the most important sources of N2O, however, understanding of how N2O emission from the detritusphere is influenced by soil properties remains elusive. Here, we evaluated ...the effects of pore architecture and soil moisture on N2O emission during the decomposition of in-situ grown roots of switchgrass, an important bioenergy crop. We combined dual isotope labeling (15C and 15N) with zymography to gain insights into the location of the microbial N2O production in soils with contrasting pore architectures. In the studied soil, the effect of soil pore architecture on N2O emissions was 6 times greater than that of soil moisture. Soil dominated by > 30 μm Ø pores (i.e., large-pore soil) had higher chitinase activity than the soil dominated by < 10 μm Ø pores (i.e., small-pore soil), especially near the decomposing roots. The chitinase activity on the decomposing roots was positively correlated with emission of root-derived N2O, indicating that N released from root decomposition was an important source of N2O. Greater N2O and N2 emission was induced by switchgrass roots in soils dominated by the large- compared to the small-pore soils. The microenvironment developed near decomposing roots of the large-pore soil also resulted in positive N2O priming. Our study challenged the traditional view on soil moisture as the main factor of N2O production. Production and emission of N2O was most intensive in microbial activity hotspots (i.e., rhizosphere legacy) in the large pores, where decomposed roots release mineral N as the main N2O source.
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•Rhizosphere soil carries a strong legacy effect as it turns into detritusphere.•Pore architecture is 6 times more important than soil water content in N2O emission.•N2O emission is most intensive in microbial activity hotspots in large pores.•Root- and soil-derived N2O emissions both occur near decomposing roots.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The peculiarities of the dynamics of the spectral indices of cardiac rhythm variability in 32 women 17-23 years of age while viewing emotional IAPS (International affective picture system) images in ...different phases of the menstrual cycle were studied. It is shown that the differences in the regulation of the heart rhythm associated with viewing emotional images of different types are manifested mainly in the follicular phase of the menstrual cycle. During this period, significant differences in viewing emotional images of different types were found in the absolute and relative power of the very low-frequency (VLF) and high-frequency (HF) component of the spectrum. In the ovulation phase, emotion-sensitive markerwas a lowfrequency spectrum component (LF), reflecting the effect of the sympathetic nervous system on cardiac rhythm. This indicator was significantly higher when viewing unpleasant images compared to pleasant and erotic visual stimuli.The contribution of the sympathetic division to the regulation of cardiac rhythm was observed during viewing of negative and neutral images, and only the viewing of erotic images was characterized by an increase in parasympathetic activity, which was accompaniedwith the increased power of the high-frequency component of the spectrum (HF) reducing the proportion of LF/HF and respiratory rate. The study shows that during the menstrual cycle, the autonomic balance shifts toward the predominance of sympathetic regulation of the heart rhythm, which reaches a maximum in the luteal phase. In this regard, the activity level of the sympathetic link recorded by the power of the low-frequency (LF) component while viewing unpleasant images was the lowest in the follicular phase and the highest in the luteal one. No significant differences were found between the spectral indices of cardio-interval variability when viewing emotional images in the luteal phase, indicating that this period of the cycle was low informative to assess the characteristics of women's emotional response based on heart rate analysis.
There is an increasing public awareness of the relatively new and expanded industrial barium uses which are potential sources of human exposure (e.g., a shale gas development that causes an increased ...awareness of environmental exposures to barium). However, absorption of barium in exposed humans and a full spectrum of its health effects, especially among chronically exposed to moderate and low doses of barium populations, remain unclear. We suggest a systematic literature review (from 1875 to 2014) on environmental distribution of barium, its bioaccumulation, and potential and proven health impacts (in animal models and humans) to provide the information that can be used for optimization of future experimental and epidemiological studies and developing of mitigative and preventive strategies to minimize negative health effects in exposed populations. The potential health effects of barium exposure are largely based on animal studies, while epidemiological data for humans, specifically for chronic low-level exposures, are sparse. The reported health effects include cardiovascular and kidney diseases, metabolic, neurological, and mental disorders. Age, race, dietary patterns, behavioral risks (e.g., smoking), use of medications (those that interfere with absorbed barium in human organism), and specific physiological status (e.g., pregnancy) can modify barium effects on human health. Identifying, evaluating, and predicting the health effects of chronic low-level and moderate-level barium exposures in humans is challenging: Future research is needed to develop an understanding of barium bioaccumulation in order to mitigate its potential health impacts in various exposured populations. Further, while occupationally exposed at-risk populations exist, it is also important to identify potentially vulnerable subgroups among non-occupationally exposed populations (e.g., elderly, pregnant women, children) who are at higher risk of barium exposure from drinking water and food.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The structure of deterministically nanopatterned surfaces created using a combination of electron beam lithography and reactive ion etching was evaluated using small-angle neutron scattering (SANS). ...Samples exhibit 2D neutron scattering patterns that confirm the presence of ordered nanoscale cavities consistent with the targeted morphologies as well as with SEM data analysis. Comparison of SANS intensities obtained from samples in air and in contact with an aqueous phase (pure deuterium oxide, D2O, or a contrast matched mixture of D2O + H2O) reveals formation of stable gaseous nanobubbles trapped inside the cavities. The relative volume of nanobubbles depends strongly on the hydrophobicity of the cavity walls. In the case of hydrophobic surfaces, nanobubbles occupy up to 87% of the total cavity volume. The results demonstrate the high degree of sensitivity of SANS measurements for detecting and characterizing nano- and mesoscale bubbles with the volume fraction as low as ∼10–6.
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IJS, KILJ, NUK, PNG, UL, UM
Aim: to provide a literature review of the current data on various pathomechanisms of left ventricular (LV) remodeling in heart failure (HF) patients and their role in the development and progression ...of myocardial dysfunction. This paper is a first part of the review, devoted to the current state of pathophysiology of LV remodeling in HF.
Material and methods. The thematic scientific papers, published during the last decade, constituted the study material. The research methodology involved bibliosemantic method and structural and logical analysis.
Results and discussion. LV remodeling is the result of complex changes at the molecular, cellular and tissue levels, affecting the myocardial mass, geometry and performance, and ultimately leading to HF development and progression. LV systolic dysfunction occurs through the numerous mechanisms, including the defects in sarcomere function, abnormal excitation-contraction coupling and calcium homeostasis, ion channel dysfunction, mitochondrial and metabolic abnormalities, depressed cardiomyocytes survival signaling, redox pathobiology, inflammation and inadequate vasculogenesis. The term «LV diastolic dysfunction» covers the alterations in diastolic distensibility, filling or relaxation of the LV, regardless of whether LV (global) systolic function is normal or abnormal, and regardless of whether the patient has clinical manifestations of HF. The up-to-date pathophysiological paradigm of the development and progression of HF with LV diastolic dysfunction and preserved LV (global) systolic function considers systemic inflammation as a key pathomechanism of structural and functional changes of the myocardium, promoted by various cardiovascular and extracardiac conditions. In its turn, the systemic inflammation promotes endothelial dysfunction, contributing to multiple end-organ damage.
Conclusion. The deepening one`s knowledge of various pathomechanisms of LV remodeling and related myocardial dysfunction in HF patients is an important prerequisite for identifying new perspectives on further fundamental research аnd more rational designing of future clinical trials.
The paper deals with estimating radiation risks of non-cancer diseases of the circulatory system among the Chernobyl emergency workers based on data from the Russian National Medical and Dosimetric ...Registry. The results for the cohort of 61,017 people observed between 1986 and 2000 are discussed. These are essentially updated results for the similar cohort that was studied by authors earlier in 1986-1996. Newly discovered is the statistically significant dose risk of ischemic heart disease ERR Gy = 0.41, 95% CI = (0.05; 0.78). Confirmation is provided for the existence of significant dose risks for essential hypertension ERR Gy = 0.36, 95% CI = (0.005; 0.71) and cerebrovascular diseases ERR Gy = 0.45, 95% CI = (0.11; 0.80). In 1996-2000, the assessed ERR Gy for cerebrovascular diseases was 0.22 with 95% CI = (-0.15; 0.58). Special consideration is given to cerebrovascular diseases in the cohort of 29,003 emergency workers who arrived in the Chernobyl zone during the first year after the accident. The statistically significant heterogeneity of the dose risk of cerebrovascular diseases is shown as a function of the duration of stay in the Chernobyl zone: ERR Gy = 0.89 for durations of less than 6 wk, and ERR Gy = 0.39 on average. The at-risk group with respect to cerebrovascular diseases are those who received external radiation doses greater than 150 mGy in less than 6 wk RR = 1.18, 95% CI = (1.00; 1.40). For doses above 150 mGy, the statistically significant risk of cerebrovascular diseases as a function of averaged dose rate (mean daily dose) was observed: ERR per 100 mGy d = 2.17 with 95% CI = (0.64; 3.69). The duration of stay within the Chernobyl zone itself, regardless of the dose factor, had little influence on cerebrovascular disease morbidity: ERR wk = -0.002, with 95% CI = (-0.004; -0.001). The radiation risks in this large-scale cohort study were not adjusted for recognized risk factors such as excessive weight, hypercholesterolemia, smoking, alcohol consumption, and others.
The paper is devoted to the problem of the interaction between a shock wave and a thermally stratified energy source for the purpose of supersonic/hypersonic flow control realization. The effect of ...the thermally stratified energy source on a shock wave with the Mach number in the range of 6–12 is researched numerically based on the Navier-Stokes system of equations. Redistribution of specific internal energy and volume density of kinetic energy behind the wave front is investigated. Multiple manifestations of the Richtmyer-Meshkov instability has been obtained which has caused the blurring and disappearance of shock wave and contact discontinuity fronts in density fields. A study of the efficiency of using a stratified energy source instead of a homogeneous one with the same value of the full energy is carried out. The agreement with the available experimental data for the shock wave Mach number 6 has been obtained.
We study the process e + e − → e + e − η ′ in the double-tag mode and measure for the first time the γ * γ * → η ′ transition form factor F η′ ( Q 2 1 , Q 2 2 ) in the momentum-transfer range 2 < Q 2 ...1 , Q 2 2 < 60 GeV 2 . The analysis is based on a data sample corresponding to an integrated luminosity of around 469 fb − 1 collected at the PEP-II e + e − collider with the BABAR detector at center-of-mass energies near 10.6 GeV.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
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