[The 5th Wave Epub Free 127
Luther Lazaro
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Background: Coronary blood flow peaks in diastole when aortic blood pressure has fallen. Current models fail to completely explain this phenomenon. We present a new approach-using wave intensity analysis-to explain this phenomenon in normal subjects and to evaluate the effects of left ventricular hypertrophy (LVH).
Conclusions: Six waves predominantly drive human coronary blood flow. Coronary flow peaks in diastole because of the dominance of a "suction" wave generated by myocardial microcirculatory decompression. This is significantly reduced in LVH.
Background and purpose: Spasticity is a disabling complication of stroke and different noninvasive treatments are used to reduce muscle hypertonia. Shock waves are defined as a sequence of single sonic pulses largely used in the treatment of diseases involving bone and tendon as well as muscular contractures. The effect and duration of extracorporeal shock wave therapy (ESWT) was investigated on muscle hypertonia of the hand and wrist.
Methods: A total of 20 patients affected by stroke associated with severe hypertonia in upper limbs were evaluated. Placebo stimulation was performed 1 week before active stimulation in each patient. Evaluation was performed using the National Institutes of Health and Ashworth scales and video monitoring with a digital goniometer before and immediately after placebo or active stimulation. Motor nerve conduction velocity from abductor digiti minimi were recorded. Patients were monitored at 1, 4, and 12 weeks after active treatment.
Results: After active ESWT, patients showed greater improvement in flexor tone of wrist and fingers compared with placebo stimulation. At the 1- and 4-week follow-up visits, a significant decrease of passive muscle tonicity was noted on muscles in all patients receiving active treatment. At 12 weeks after therapy, 10 of the 20 patients showed persistent reduction in muscle tone. There were no adverse events associated with ESWT.
This book presents the fundamentals of the shock wave theory. The first part of the book, Chapters 1 through 5, covers the basic elements of the shock wave theory by analyzing the scalar conservation laws.
The main focus of the analysis is on the explicit solution behavior. This first part of the book requires only a course in multi-variable calculus, and can be used as a text for an undergraduate topics course. In the second part of the book, Chapters 6 through 9, this general theory is used to study systems of hyperbolic conservation laws. This is a most significant well-posedness theory for weak solutions of quasilinear evolutionary partial differential equations. The final part of the book, Chapters 10 through 14, returns to the original subject of the shock wave theory by focusing on specific physical models. Potentially interesting questions and research directions are also raised in these chapters.
The book can serve as an introductory text for advanced undergraduate students and for graduate students in mathematics, engineering, and physical sciences. Each chapter ends with suggestions for further reading and exercises for students.
This book is recommended primarily to researchers and doctoral students. It is a unique reference about the well-posedness theory of the Cauchy problem for hyperbolic systems of conservation laws. It gives a unified presentation of the program carried out by Liu and his collaborators (often former students of him), which was so far disseminated into dozens [of] papers, if not hundreds.
Near-surface seismic shear wave is a basic tool for seismic investigations. However, its frequency-dependent property is not fully investigated, especially by the in situ observation method. Here, we develop the seismic interferometry with a moving frequency window to process the natural seismic signals recorded by the KiK-net network. It is observed that the phase velocity of the shear wave decreases sharply as the frequency increases in the low-frequency range, and remains constant in the high-frequency range. The observed dispersion phenomenon presents a challenge to existing site effect prediction theories, while also providing an observational reference for understanding how the shear wave propagates in near-surface sediment.
Near-surface seismic shear wave is widely used in the in the study of site effect, seismic hazard analysis, seismic engineering design, seismic exploration, and seismic tomography (Bonilla et al. 2019; Peng and Ben-Zion 2006; Field et al. 1997; Rydelek and Tuttle 2004; Wang et al. 2021; Kim and Lekic 2019; Kaklamanos and Bradley 2018; Chabyshova and Goloshubin 2014). Clarifying the frequency-dependent properties of near-surface seismic shear wave is the basis for the higher precision seismic investigations. Theoretical and the experimental researches on this aspect have been ongoing for decades (Aki and Richards 1980; Ba et al. 2016; Borgomano et al. 2017; Mller et al. 2010), but the research based on the in situ observations are sparse, because it is generally believed that the natural ground motion has strong instability and randomness, making it difficult to separate different frequency components for analysis (Kaklamanos and Bradley 2018; Zhu et al. 2022; Thompson et al. 2012).
In this study, we aim to estimate the frequency-dependent velocity of near-surface seismic shear wave by performing the seismic interferometry to the natural seismic signals recorded at 6 sites in Japan. Firstly, we introduced the seismic data collected and provided the technical details of the moving-frequency-window seismic interferometry. Secondly, we calculated the frequency-varying site empirical transfer function and extracted the travel time curve with respect to frequency. Thirdly, we obtained the frequency-dependent velocity and analyzed the dispersion property of the shear wave in near-surface sediment.
Seismic interferometry is a technique that calculates the empirical transfer function and extracts the travel time of the seismic wave based on the wavefield information (Curtis et al. 2006). According to its calculation principles, it can be roughly divided into two categories: those based on the cross-correlation (convolution) and those based on the deconvolution (Bonilla et al. 2019; Wang et al. 2021; Nakata and Snieder 2012; Miyazawa et al. 2008). Considering that the seismic interferometry based on the deconvolution can eliminate the influence of the source and path effects, and only focuses on the site sediment (Nakata and Snieder 2012), we choose the seismic interferometry based on the deconvolution to process the seismic signals. Equation of the seismic interferometry based on deconvolution is as follows:
Application example of the method is illustrated in Fig. 2, and the steps are introduced here briefly. First, the Fourier transform is applied to the seismic signals recorded by the KiK-net station at the borehole and surface, respectively. Second, the surface wave field is divided by the borehole wave field in the frequency domain to obtain the deconvolved waveform in the frequency domain as shown in Eq. (1). Third, a 0.5-Hz-width moving bandpass filter with 0.1 Hz step length is applied to the entire waveform. Fourth, we apply the inverse Fourier transform for every filtered waveform to obtain the transfer function in the time domain. Fifth, the transfer function is interpolated 1:10,000 to improve the resolution of the result.
Divided the time delay by the borehole depth, Fig. 4 shows the calculated phase velocity of the six stations. We define the frequency corresponding to a 2% increase in comparison to the non-dispersive value as the threshold at which the dispersion phenomenon disappears. The thresholds of the six stations are 18.9 Hz, 9 Hz, 15.8 Hz, 1.55 Hz, 1.36 Hz, and 1.68 Hz for the six stations, which implies that the wavelength are about 0.67, 0.94, 0.74. 0.70, 0.54, and 0.49 times the borehole depth. In addition to the non-dispersive threshold and the one-wavelength point, we have also selected the 2 times wavelength point and 5 times wavelength point as features to illustrate the results. In general, the corresponding phase velocity is approximately 1.51 and 11.21 times the non-dispersive value (Additional file 1: Fig. S4).
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