Current Issue : January - March Volume : 2017 Issue Number : 1 Articles : 5 Articles
Pulse wave contains human physiological and pathological information. Different\npeople will exhibit different characteristics, and hence determining the characteristic\npoints of the pulse wave of human physiological health makes sense. It is common\nthat we extract the characteristic value of pulse wave signal with the method based on\nwavelet transform on a small scale, and then determine the locations of the characteristic\npoints by modulus maxima and modulus minima. Before determining characteristic\nvalue by detecting modulus maxima and modulus minima, we need to determine\nevery period of the pulse wave. This paper presents a new kind of adaptive\nthreshold determination method which is more effective. It can accurately determine\nevery period of the pulse wave, and then extract characteristic values by modulus\nmaxima and modulus minima in every period of the pulse wave. The method presented\nin this paper promotes the research utilizing pulse wave on health life....
Background: Inhaled nitric oxide (NO) is a selective pulmonary vasodilator used\nprimarily in the critical care setting for patients concurrently supported by invasive or\nnoninvasive positive pressure ventilation. NO delivery devices interface with ventilator\nbreathing circuits to inject NO in proportion with the flow of air/oxygen through the\ncircuit, in order to maintain a constant, target concentration of inhaled NO.\nMethods: In the present article, a NO injection and mixing element is presented. The\ndevice borrows from the design of static elements to promote rapid mixing of injected\nNO-containing gas with breathing circuit gases. Bench experiments are reported to\ndemonstrate the improved mixing afforded by the injection and mixing element, as\ncompared with conventional breathing circuit adapters, for NO injection into breathing\ncircuits. Computational fluid dynamics simulations are also presented to illustrate mixing\npatterns and nitrogen dioxide production within the element.\nResults: Over the range of air flow rates and target NO concentrations investigated,\nmixing length, defined as the downstream distance required for NO concentration\nto reach within �±5 % of the target concentration, was as high as 47 cm for the conventional\nbreathing circuit adapters, but did not exceed 7.8 cm for the injection and\nmixing element.\nConclusion: The injection and mixing element has potential to improve ease of use,\ncompatibility and safety of inhaled NO administration with mechanical ventilators and\ngas delivery devices....
Background: Coronary hemodynamics and physiology specific for bifurcation lesions\nwas not well understood. To investigate the influence of the bifurcation angle on the\nintracoronary hemodynamics of side branch (SB) lesions computational fluid dynamics\nsimulations were performed.\nMethods: A parametric model representing a left anterior descendingââ?¬â?first diagonal\ncoronary bifurcation lesion was created according to the literature. Diameters obeyed\nfractal branching laws. Proximal and distal main branch (DMB) stenoses were both set\nat 60 %. We varied the distal bifurcation angles (40Ã?°, 55Ã?°, and 70Ã?°), the flow splits to the\nDMB and SB (55 %:45 %, 65 %:35 %, and 75 %:25 %), and the SB stenoses (40, 60, and\n80 %), resulting in 27 simulations. Fractional flow reserve, defined as the ratio between\nthe mean distal stenosis and mean aortic pressure during maximal hyperemia, was\ncalculated for the DMB and SB (FFRSB) for all simulations.\nResults: The largest differences in FFRSB comparing the largest and smallest bifurcation\nangles were 0.02 (in cases with 40 % SB stenosis, irrespective of the assumed\nflow split) and 0.05 (in cases with 60 % SB stenosis, flow split 55 %:45 %). When the SB\nstenosis was 80 %, the difference in FFRSB between the largest and smallest bifurcation\nangle was 0.33 (flow split 55 %:45 %). By describing the Ã?â?PSB\nâË?â??QSB relationship using a\nquadratic curve for cases with 80 % SB stenosis, we found that the curve was steeper\n(i.e. higher flow resistance) when bifurcation angle increases (Ã?â?P = 0.451*Q + 0.010*Q2\nand Ã?â?P = 0.687*Q + 0.017*Q2 for 40Ã?° and 70Ã?° bifurcation angle, respectively). Our analyses\nrevealed complex hemodynamics in all cases with evident counter-rotating helical\nflow structures. Larger bifurcation angles resulted in more pronounced helical flow\nstructures (i.e. higher helicity intensity), when 60 or 80 % SB stenoses were present. A\ngood correlation (R2 = 0.80) between the SB pressure drop and helicity intensity was\nalso found.\nConclusions: Our analyses showed that, in bifurcation lesions with 60 % MB stenosis\nand 80 % SB stenosis, SB pressure drop is higher for larger bifurcation angles\nsuggesting higher flow resistance (i.e. curves describing the Ã?â?PSB\nâË?â??QSB relationship\nbeing steeper). When the SB stenosis is mild (40 %) or moderate (60 %), SB resistance is minimally influenced by the bifurcation angle, with differences not being clinically\nmeaningful. Our findings also highlighted the complex interplay between anatomy,\npressure drops, and blood flow helicity in bifurcations....
The impact of the electromagnetic waves (EM) on human neurons (HN) has been under investigation\nfor decades, in efforts to understand the impact of cell phones (radiation) on human health, or\nradiation absorption by HN for medical diagnosis and treatment. Research issues including the\nwave frequency, power intensity, reflections and scattering, and penetration depths are of important\nconsiderations to be incorporated into the research study. In this study, computer simulation\nfor the EM exposure to HN was studied for the purpose of determining the upper limits of the electric\nand magnetic field intensities, power consumption, reflections and transmissions, and the\nchange in temperature resulting from the power absorption by human neurons. Both high frequency\nstructural simulators (HFSS) from ANSYS software, and COMSOL multi-physics were used\nfor the simulation of the EM transmissions and reflections, and the temperature profile within the\ncells, respectively. For the temperature profile estimation, the study considers an electrical source\nof 0.5 watt input power, 64 MHz. The EM simulation was looking into the uniformity of the fields\nwithin the sample cells. The size of the waveguide was set to be appropriate for a small animal\nmodel to be conducted in the future. The incident power was fully transmitted throughout the\nwaveguide, and less than 1% reflections were observed from the simulation. The minimum reflected\npower near the sample under investigation was found to be with negligible reflected field\nstrengths. The temperature profile resulting from the COMSOL simulation was found to be near\n0.25 \nting no change in temperature on the neuro cells under the EM exposure. The pa-per details the simulation results for the EM response determined by HFSS, and temperature profile\nsimulated by COMSOL....
Background: In this study, a new algorithm was developed for estimating the pump\noutflow of a pneumatic ventricular assist device (p-VAD). The pump outflow estimation\nalgorithm was derived from the ideal gas equation and determined the change in\nblood-sac volume of a p-VAD using two external pressure sensors.\nObjectives: Based on in vitro experiments, the algorithm was revised to consider the\neffects of structural compliance caused by volume changes in an implanted unit, an air\ndriveline, and the pressure difference between the sensors and the implanted unit.\nMethods: In animal experiments, p-VADs were connected to the left ventricles and\nthe descending aorta of three calves (70ââ?¬â??100 kg). Their outflows were estimated using\nthe new algorithm and compared to the results obtained using an ultrasonic blood\nflow meter (UBF) (TS-410, Transonic Systems Inc., Ithaca, NY, USA).\nResults: The estimated and measured values had a Pearsonââ?¬â?¢s correlation coefficient\nof 0.864. The pressure sensors were installed at the external controller and connected\nto the air driveline on the same side as the external actuator, which made the sensors\neasy to manage....
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