45 research outputs found

    On Formation of Anthrasemiquinone in the Conditions of Wood Alkaline Pulping

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    Electron spin resonance (ESR) and electronic absorbance spectral experiments demonstrate that reversible temperature variation of anion-radica1 concentration in the system anthraqui; none (AQ) - anthrasemiquinone (AS) - anthrahydroquinone (AHQ) in aqueous alka1i is a property of that system and not of the more complicated catalyst-wood system. Lignin model compounds present in low concentrations have no influence on this variation. A raise of radical concentration is accompanied by a change of the solution colour from red into yellow. In pulping conditions AQ can be reduced either by the hydrocarbon or by the lignin component of wood, probably also by numerous organic compounds and even by the alka1i itself. As a result of this process, an AQ-AS-AHQ system is being formed

    The global picture of self-similar and not self-similar decay in Burgers Turbulence

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    This paper continue earlier investigations on the decay of Burgers turbulence in one dimension from Gaussian random initial conditions of the power-law spectral type E0(k)âˆŒâˆŁk∣nE_0(k)\sim|k|^n. Depending on the power nn, different characteristic regions are distinguished. The main focus of this paper is to delineate the regions in wave-number kk and time tt in which self-similarity can (and cannot) be observed, taking into account small-kk and large-kk cutoffs. The evolution of the spectrum can be inferred using physical arguments describing the competition between the initial spectrum and the new frequencies generated by the dynamics. For large wavenumbers, we always have k−2k^{-2} region, associated to the shocks. When nn is less than one, the large-scale part of the spectrum is preserved in time and the global evolution is self-similar, so that scaling arguments perfectly predict the behavior in time of the energy and of the integral scale. If nn is larger than two, the spectrum tends for long times to a universal scaling form independent of the initial conditions, with universal behavior k2k^2 at small wavenumbers. In the interval 2<n2<n the leading behaviour is self-similar, independent of nn and with universal behavior k2k^2 at small wavenumber. When 1<n<21<n<2, the spectrum has three scaling regions : first, a ∣k∣n|k|^n region at very small kk\ms1 with a time-independent constant, second, a k2k^2 region at intermediate wavenumbers, finally, the usual k−2k^{-2} region. In the remaining interval, n<−3n<-3 the small-kk cutoff dominates, and nn also plays no role. We find also (numerically) the subleading term ∌k2\sim k^2 in the evolution of the spectrum in the interval −3<n<1-3<n<1. High-resolution numerical simulations have been performed confirming both scaling predictions and analytical asymptotic theory.Comment: 14 pages, 19 figure

    Altimetry for the future: Building on 25 years of progress

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    In 2018 we celebrated 25 years of development of radar altimetry, and the progress achieved by this methodology in the fields of global and coastal oceanography, hydrology, geodesy and cryospheric sciences. Many symbolic major events have celebrated these developments, e.g., in Venice, Italy, the 15th (2006) and 20th (2012) years of progress and more recently, in 2018, in Ponta Delgada, Portugal, 25 Years of Progress in Radar Altimetry. On this latter occasion it was decided to collect contributions of scientists, engineers and managers involved in the worldwide altimetry community to depict the state of altimetry and propose recommendations for the altimetry of the future. This paper summarizes contributions and recommendations that were collected and provides guidance for future mission design, research activities, and sustainable operational radar altimetry data exploitation. Recommendations provided are fundamental for optimizing further scientific and operational advances of oceanographic observations by altimetry, including requirements for spatial and temporal resolution of altimetric measurements, their accuracy and continuity. There are also new challenges and new openings mentioned in the paper that are particularly crucial for observations at higher latitudes, for coastal oceanography, for cryospheric studies and for hydrology. The paper starts with a general introduction followed by a section on Earth System Science including Ocean Dynamics, Sea Level, the Coastal Ocean, Hydrology, the Cryosphere and Polar Oceans and the ‘‘Green” Ocean, extending the frontier from biogeochemistry to marine ecology. Applications are described in a subsequent section, which covers Operational Oceanography, Weather, Hurricane Wave and Wind Forecasting, Climate projection. Instruments’ development and satellite missions’ evolutions are described in a fourth section. A fifth section covers the key observations that altimeters provide and their potential complements, from other Earth observation measurements to in situ data. Section 6 identifies the data and methods and provides some accuracy and resolution requirements for the wet tropospheric correction, the orbit and other geodetic requirements, the Mean Sea Surface, Geoid and Mean Dynamic Topography, Calibration and Validation, data accuracy, data access and handling (including the DUACS system). Section 7 brings a transversal view on scales, integration, artificial intelligence, and capacity building (education and training). Section 8 reviews the programmatic issues followed by a conclusion

    Altimetry for the future: building on 25 years of progress

    Get PDF
    In 2018 we celebrated 25 years of development of radar altimetry, and the progress achieved by this methodology in the fields of global and coastal oceanography, hydrology, geodesy and cryospheric sciences. Many symbolic major events have celebrated these developments, e.g., in Venice, Italy, the 15th (2006) and 20th (2012) years of progress and more recently, in 2018, in Ponta Delgada, Portugal, 25 Years of Progress in Radar Altimetry. On this latter occasion it was decided to collect contributions of scientists, engineers and managers involved in the worldwide altimetry community to depict the state of altimetry and propose recommendations for the altimetry of the future. This paper summarizes contributions and recommendations that were collected and provides guidance for future mission design, research activities, and sustainable operational radar altimetry data exploitation. Recommendations provided are fundamental for optimizing further scientific and operational advances of oceanographic observations by altimetry, including requirements for spatial and temporal resolution of altimetric measurements, their accuracy and continuity. There are also new challenges and new openings mentioned in the paper that are particularly crucial for observations at higher latitudes, for coastal oceanography, for cryospheric studies and for hydrology. The paper starts with a general introduction followed by a section on Earth System Science including Ocean Dynamics, Sea Level, the Coastal Ocean, Hydrology, the Cryosphere and Polar Oceans and the “Green” Ocean, extending the frontier from biogeochemistry to marine ecology. Applications are described in a subsequent section, which covers Operational Oceanography, Weather, Hurricane Wave and Wind Forecasting, Climate projection. Instruments’ development and satellite missions’ evolutions are described in a fourth section. A fifth section covers the key observations that altimeters provide and their potential complements, from other Earth observation measurements to in situ data. Section 6 identifies the data and methods and provides some accuracy and resolution requirements for the wet tropospheric correction, the orbit and other geodetic requirements, the Mean Sea Surface, Geoid and Mean Dynamic Topography, Calibration and Validation, data accuracy, data access and handling (including the DUACS system). Section 7 brings a transversal view on scales, integration, artificial intelligence, and capacity building (education and training). Section 8 reviews the programmatic issues followed by a conclusion

    Omecamtiv mecarbil in chronic heart failure with reduced ejection fraction, GALACTIC‐HF: baseline characteristics and comparison with contemporary clinical trials

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    Aims: The safety and efficacy of the novel selective cardiac myosin activator, omecamtiv mecarbil, in patients with heart failure with reduced ejection fraction (HFrEF) is tested in the Global Approach to Lowering Adverse Cardiac outcomes Through Improving Contractility in Heart Failure (GALACTIC‐HF) trial. Here we describe the baseline characteristics of participants in GALACTIC‐HF and how these compare with other contemporary trials. Methods and Results: Adults with established HFrEF, New York Heart Association functional class (NYHA) ≄ II, EF ≀35%, elevated natriuretic peptides and either current hospitalization for HF or history of hospitalization/ emergency department visit for HF within a year were randomized to either placebo or omecamtiv mecarbil (pharmacokinetic‐guided dosing: 25, 37.5 or 50 mg bid). 8256 patients [male (79%), non‐white (22%), mean age 65 years] were enrolled with a mean EF 27%, ischemic etiology in 54%, NYHA II 53% and III/IV 47%, and median NT‐proBNP 1971 pg/mL. HF therapies at baseline were among the most effectively employed in contemporary HF trials. GALACTIC‐HF randomized patients representative of recent HF registries and trials with substantial numbers of patients also having characteristics understudied in previous trials including more from North America (n = 1386), enrolled as inpatients (n = 2084), systolic blood pressure &lt; 100 mmHg (n = 1127), estimated glomerular filtration rate &lt; 30 mL/min/1.73 m2 (n = 528), and treated with sacubitril‐valsartan at baseline (n = 1594). Conclusions: GALACTIC‐HF enrolled a well‐treated, high‐risk population from both inpatient and outpatient settings, which will provide a definitive evaluation of the efficacy and safety of this novel therapy, as well as informing its potential future implementation

    A new point on ECG: point L as identifier of rapid and slow ejection phases boundary

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    Aims Description of rapid and slow ejection phases in the cardiac cycle. Materials and methods The theory of cardiac cycle phase analysis and mathematical equations of hemodynamics were used in the paper. The equations were employed to verify the balance of the phase-related diastolic and systolic blood volumes reliant on phase durations, and the identification of boundaries of the cardiac cycle phases on the ECG. Further, synchronous ECG & RHEO recording was used. Aortic blood filling was studied in the stated phases. Results The location of boundaries of rapid and slow ejection phases is traced. The boundaries did not have a precise definition before. Thus, a new symbol, the L point, on the ECG has been introduced to identify the boundaries of phases S-L, L-j. Conclusion Previously the location of point j on the ECG was impossible to identify. It was considered as a hypothermic wave on the ECG that could not always be traced. Point j was defined as the j (Osborn) wave. Thereby the location of boundaries of rapid and slow ejection phases, where volumetric parameters were equal to the stroke volume, was not accurately identified. The research enabled detecting the ECG recording criteria of the rapid and slow ejection phases. The results of the present research are published for the first time

    ECG as a quest for extracting new data: non-invasive measurement of acid-alkaline parameters

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    Aims A cardiac muscle performance assessment in terms of acid-alkaline balance has never been carried out before. The studies show it is possible to evaluate indirectly aerobic, anaerobic and phosphocreatine processes in the cardiac muscle using ECG only. The aim is to study the capabilities of acid-alkaline balance measurement in the cardiac muscle using ECG only, in combination with the heart cycle phase analysis. Materials and methods The ECG of the ascending aorta is recorded with Cardiocode device. Amplitudes of the derivatives of leading and trailing edge of R, L and j waves are measured. The QRS complex amplitude depends on the amplitudes of the septum and myocardium muscles contractions. The septum is contracted because of the lesser resistance since the myocardium muscles are not loaded yet. When the myocardium muscles are contracted, they take a heavier load since the septum remains under static strain. It allows evaluating the difference in the energy consumption for each group of the muscles according to the respective ECG derivative. It will suffice to compare the amplitudes of the first derivative characterizing the muscle contractility rate during Q–R and R–S periods. Results Over 500 patients were examined. As a result, ranges of every biochemical reaction changes have been established. The ranges of energy consumption assessment for the biochemical processes featuring the biochemical reactions in cardiac muscles are defined. Conclusion The ECG heart cycle phase analysis allows obtaining the acid-alkaline balance data of biochemical reactions governing the cardiac muscle contraction that is an important diagnostic marker

    Heart and aortic baroreceptors: operation in providing hemodynamic processes in cardiovascular system

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    Aims Up to the present, ECGs have been classified on the basis of the analysis of the ECG curve shape. But this made impossible to classify many ECG shapes. The most promising methods for the classification must evaluate each of the 10 cardiac cycle phases both by their functions and hemodynamic parameters. The aim hereof is to develop the new classification principles for all possible ECG shape variations. Materials and methods The heart cycle phase analysis method is used to calculate the hemodynamic parameters in each of 10 phases, like the phase-related blood volumes and the level of contraction of the corresponding cardiovascular musculature determining its function dynamics in the cardiac cycle phase structure related to the compensation mechanism for maintaining normal hemodynamics. Results An ECG phase changes periodic table consisting of 10 groups of the actual ECG curves typical for the corresponding pathologies is proposed. Each group contains 4 levels of characteristic phase changes. Conclusion The ECG phase changes periodic table is the first attempt to classify the great variety of the ECG shapes. In this case the proposed system requires further investigations. It has been demonstrated that the theoretical concept of the table is in compliance with practice. Further it is planned to improve characteristics of every group and every level

    Criteria of identification of individual heart cycle phases on ECG

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    Aims Criteria of identification of individual heart cycle phases according to an ECG curve are described in this paper. Materials and methods For this study, a single-lead system ECG is used only. Its distinctive feature is that an ECG signal is recorded within the body surface area of the ascending aorta. Using the theory of biological system process continuity, the individual heart cycle phase boundaries are determined at those points of the cardiac signals where we deal with an energy process transition in the cardiovascular system from the process of the energy build-up to its attenuation, and vice versa. The transition points are identified by us by mathematical differentiation of the ECG signals, and, as a result, they correspond to extrema of the ECG derivative. Some individual heart cycle phases are found according to maxima on the derivative, others are identified according to minima on the derivative curve, respectively. Results The method of application of the ECG derivatives allows to capture individual heart cycle phases in a very precise manner. Utilization of the ECG derivatives is a prerequisite for computer-assisted processing of the data to deliver measurements of durations of every heart cycle phase. Conclusion Using the ECG derivatives for fixing every heart cycle phase makes possible to fill up the gaps in the theory of phase analysis and avoid misinterpretations of any type of the ECG phase structures

    Theoretical principles of cardiometry

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    Aims The article aims at describing the theoretical principles of cardiometry as a fundamentally new scientific field which enables the accurate measurement of the cardiovascular system parameters. Materials and methods Cardiometry is based on the mathematical model of hemodynamic processes. The model is described by G. Poyedintsev and O. Voronova equations. The variable values in these equations are the cardiac cycle phase durations recorded on the ECG. An original ECG lead of the ascending aorta reflects all the processes of the heart performance. Thus, it is possible to calculate the phase blood volumes. This method is an accurate indirect measurement method. The synchronous recording of the ascending aorta ECG and Rheogram enables monitoring of the compensation mechanism responsible for the normal hemodynamic performance. Results An innovative mathematical model of hemodynamics providing the creation of an innovative indirect method for measurement of the cardiovascular system parameters was developed. Conclusion The innovative method of cardiovascular system diagnostics enables to measure 7 main hemodynamic parameters using noninvasive technology for qualitative evaluation of 12 functions of cardiovascular system performance and general assessment of coronary flow status
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