Search

OBJECTIVE Measurements of pulse wave velocity are generally thought to be too impractical for clinical routine. This study aimed to develop a method that can be performed during routine 12-channel ECG. METHODS A 12-channel ECG simultaneously supplies arterial impedance plethysmographic signals from the extremities beside segmental multifrequency impedance measurements for obtaining body composition. The origin of the plethysmographic signal (volume wave) at the arms and legs was determined at the level of the elbows and the knees. The volume wave velocity (VWV) at the aorta and femoral arteries was calculated from the time difference of the plethysmographic signals between arms and legs. RESULTS Automated measurement of VWV was highly reproducible (r = 0.96). In 107 participants in perfect health, VWV in different models was positively related to age, physiological hemoglobin A 1C, triglycerides, normal standardized unattended blood pressure, but not to physiological low-density lipoprotein-cholesterol and high-density lipoprotein-cholesterol. Aortofemoral VWV was significantly higher in patients with established coronary artery disease than in healthy controls of the same age group (18.1 ± 5.8 vs. 11.9 ± 1.7 m/s, P

Background: The lack of acceptance in clinical routine represents a major obstacle for carotid-femoral pulse wave velocity (cfPWV) measurements. We thought to include PWV measurements into the 12-channel ECG, which is performed routinely. Methods: Using the conventional electrode position for the 12 channel ECG, arterial impedance plethysmographic signals were obtained from the four extremities at 40 kHz [1]. It was confirmed that the obtained pulse synchronous volume waves originate at the level of the elbow and the knee. In analogy to cfPWV measurements, the volume wave velocity at the aorta and femoral arteries (VWVtorso) was calculated from the time differences of the plethysmographic signals between arms and legs. Results: Transit times of R-wave to volume wave at the leg were longer but closely related to tonometrically derived transit times (199 ± 26 vs 134 ± 24 m/sec, n = 115, r = 0.93, p < 0.001). VWVtorso in 115 participants was higher than tonometrically determined cfPWV, (13.2 ± 5.81 vs 8.8 ± 2.98, ± SD, p < 0.001), since muscular arteries are included in VWVtorso. VWVtorso was measured in 825 healthy participants and patients with cardiovascular diseases (aged 16 to 97 years) (Figure 1). In stepwise multiple regression analysis, VWVtorso was found to be related positively to known cardiovascular risk factors such as age, blood pressure, HbA1C and LDL-cholesterol (p < 0.001 for all) and also negatively to appendicular muscle mass [2]. VWVtorso corresponds in its physiological determinants closely to those of cfPWV. Figure 1 Conclusion: These background arterial impedance plethysmographic measurements yielding VWVtorso, made without time delay during routine 12 channel ECG, show promise for large scale, routine clinical assessment of large artery function.

Introduction: Pulse wave velocity or (or VWV) may relate to muscle mass and body fat. We have included measurements for the above in the routine 12 channel ECG. Methods: A 12 channel ECG supplies impedance plethysmographic measurements at the four extremities at 40 kHz [1]. From these VWW was derived in analogy to carotid femoral PWV. Impedance measurements at 5, 40 and 400 kHz in six body segments are also provided [2]. From these AppMM and body fat were measured in 123 participants without diabetes and CHF and in 72 patients with CHF (NYHA class 2 to 4). Results: In multiple backward stepwise regression analysis VWV was related positively to age, standardized systolic blood pressure [3] and negatively to AppMM index (total r = 0.83, p < 0.001) but not to body fat. Discussion: The relation between VWV and the degree of sarcopenia in CHF reveals the importance of muscularity for aortic health.

We demonstrate a novel sterilization technique that sterilizes medical instruments stored in medical containers by generating a microwave-excited volume-wave plasma inside medical containers using a planar microwave launcher. We confirmed that a plasma was generated inside the medical container by the microwaves transmitted through the heat-resistant plastic lid of the container. A Langmuir probe was used to study the characteristics of the microwave-excited volume-wave plasma generated inside the container. The inactivation characteristics of Geobacillus stearothermophilus spores set inside the medical container were also investigated. 2.3 10 spores were inactivated after irradiation for 40min or longer by a plasma generated in a simulated airmixture. This inactivation time could be reduced to 30min by adding water vapor to the airsimulated plasma.

This paper presents a theoretical investigation of the effects of the induced uniaxial magnetic anisotropy on Bragg diffraction and mode conversion of a guided optical wave (GOW) by a magnetostatic backward volume wave (MSBVW). The cases of both the easy axis normal and parallel to the film have been considered. The numerical results for a Bi-doped yttrium–iron–garnet–gadolinium–gallium–garnet (YIG–GGG) waveguide show that the induced uniaxial anisotropy has significant effects on the mode conversion efficiency of GOW and magneto-optic coupling bandwidth. In particular, the induced uniaxial perpendicular anisotropy can enhance the mode conversion efficiency and magneto-optical bandwidth. Thus, the performances of MSBVW-based magneto-optical waveguides can be improved by using a magnetic film that possesses the induced uniaxial perpendicular anisotropy.

The capability of efficient millimeter and submillimeter wavelength generation in Cherenkov like oscillators with multistage grating is discussed in this article. The prototype of W-band oscillator with nonuniform grating has been presented. The dispersion calculations of the multistage grating in the waveguide and coupling impedance have been carried out. The simulations of self electric fields distribution of the waveguide loaded by multistage grating were performed.

Magneto-optic interactions between guided optical waves and nonlinear magnetostatic forward volume waves are studied. For the discussed configuration, when the rf input power reaches 33 dBm and the frequency is lower than 4.2 GHz, the power level of the magnetostatic forward volume wave exceeds the power threshold of the four-magnon process, and the nonlinear magneto-optic dynamic characteristics due to the magnetostatic forward volume wave instability are predicted. The theoretical pattern is supported by experimental results on the magneto-optic mode conversion.

It is shown theoretically and experimentally that a tunable oscillator without spurious oscillations can be obtained by using a magnetostatic forward-volume wave resonator with wide strip transducers. First, the equivalent circuit of a rectangular resonator is presented and the unloaded Q and the external Q are expressed in terms of the dimensions and the material constants of the resonator. By means of this expression, the condition is derived for selective excitation of the dominant mode and for suppression of the higher-order modes. A 5-GHz tunable oscillator using this resonator was fabricated. It was demonstrated that stable oscillation characteristics without spurious oscillations can be obtained.

The conditions for the excitation of volume wave solitons and self induced transparency in magnetostatic volume wave (MSW) delay lines will be discussed and compared with experimental results. The dispersion and nonlinearity characteristics of compact device structures will be analytically derived in the one and two ground plane configurations, and their influence on the onset of a solitonic behavior will be analyzed in some detail. >

An analysis of the signal reflections originating at the garnet film ends and of the triple transit between the microstrip transducers in magnetostatic volume wave delay lines has been performed. The influence of those effects on the band shape and on the insertion loss of magnetostatic wave devices has been inferred and compared with experimental results. In this framework, the possible utilization of the reflections for filterbank applications is also proposed.

High-efficiency single-order grating coupling between an optical waveguided mode and a volume wave is achieved by means of a double-sided corrugated cover film that has phase-shifted undulations. A greater than 90% outcoupling ratio into air is demonstrated for weakly guiding ion-exchanged waveguides. The conditions for efficient coupling and the tolerances on them are established.

A guided-wave magneto-optic (MO) Bragg cell modulator that utilizes a magnetostatic forward volume wave (MSFVW) oscillator through a feedback loop is reported. The carrier frequency of the MSFVW signals involved in the MO interaction is tuned linearly from 2.112 to 3.274 GHz by increasing an external bias magnetic field from 2350 to 2900 Oe. Compared with a conventional delay line-based MO Bragg cell modulator, the oscillator-based MO modulator can provide higher diffraction efficiency by twofold to fourfold owing to reduction of insertion losses in the MSFVW oscillator. Furthermore, such oscillator-type MO modulator can be more easily integrated with other monolithic microwave integrated circuit components.

The present article reports a theoretical study of nondispersive magnetostatic forward volume wave (MSFVW) propagation in a double-layered yttrium–iron–garnet (YIG)-film structure consisting of two YIG films separated by a dielectric layer. Numerical computations are presented that show that a significant improvement in bandwidth for nondispersive MSFVW propagation can be obtained in the present separated double-layered YIG-film structure over the previously reported double-layered YIG-film geometry wherein the two YIG films were in direct contact.

A design method of the input impedance for magnetostatic forward volume wave microstrip transducer shot circuited at one end is offered. The results of calculation of input impedance and input VSWR for magnetostatic forward volume wave microstrip transducers with matching networks, containing shot - circuit stubs, are presented.

The results of radiation impedance design of magnetostatic forward volume wave microstrip transducer are presented in this report. It was analysed the radiation impedance as a function of frequency for microstrip lines with different strip width and distance between the line conductors and the surface of magnetized ferrite film.

The results of radiation resistance design of magnetostatic forward volume wave multistrip transducer are presented in this report. It was analysed the radiation resistance as a function of frequency for multistrip lines with different number strips and distance between the line conductors and the surface of magnetized ferrite film.

The present article reports a theoretical study of the TM0⇥TE0 mode conversion of laser light through Bragg diffraction by higher order magnetostatic forward volume waves (MSFVWs) in a layered yttrium iron garnet (YIG) film geometry. It is found that this mode conversion can be significant, thereby somewhat mitigating the previously reported advantage of YIG film layering, i.e., layering affords a significant improvement in the bandwidth for magneto-optic coupling. Computations of the level of magneto-optic (MO) coupling caused by higher order MSFVWs excited by a microstrip transducer in a double YIG film layered structure are presented. The use of a triple YIG film layered geometry with lifted transducers for suppressing the unwanted effect of higher order MSFVW modes on the MO coupling is discussed.

The parametric amplification of 4.01 GHz, 22 ns wide microwave magnetic envelope (MME)backward volume wave pulses by parallel pumping has been realized in yttrium iron garnet (YIG)films. The parametric parallel pumping was achieved with 15–23 ns wide pulses applied to a strip lineresonator at a frequency v

The first experimental results on a nondispersive, bandwidth tunable magnetostatic wave (MSW) filter using the forward and backward volume wave (BW) propagation at X-band are shown and compared with theoretical predictions. In order to build up a configuration as simple as possible including just two coupled filters, two delay lines with opposite frequency behavior have been utilized. By using this solution, the possibility for tuning BW up to 400 MHz is achieved. It is concluded that the MSW filter configuration considered is suitable for BW tunable, nondispersive device applications. However, the filter needs improvements to optimize the band shape, especially to steepen the low-frequency side and to minimize the ripple amplitude. >

A magnetostatic forward volume wave delay line was divided into sections each with a different ground plane spacing. The length of each section was optimized so that the total group delay, i.e., the summation of the delay in each section, showed a minimum phase error from a quadratic phase with frequency characteristic. Using this technique a delay line with 600 MHz bandwidth, 50 nS differential delay and phase error < +- 16° has been demonstrated at X-band.

The frequency shift due to temperature variation in the microwave response of a magnetostatic forward volume wave YIG straight edge resonator in a band-stop configuration filter has been measured. In particular, the effect of the angular variation /spl theta//sub e/ of the dc magnetic bias field H/sub e/ with respect to the film plane on the temperature frequency shift has been experimentally tested, and it has been demonstrated that thermostability improvement can be obtained as a function of /spl theta//sub e/. Moreover, a good agreement between theoretical expectations and experimental findings has been obtained.

Recently, attention has been paid to the creation of new generator and amplifier modifications which use diffraction (Smith-Purcell) and Cerencov radiations. In particular, an amplifier model based on a two-mirror open waveguide (OW) stimulated by diffraction volume wave radiation was investigated (Vorobjov, G.S., et al., 1998; 2001). The paper describes theoretical and experimental investigations of an amplifier electrodynamics system, which consists of a periodic structure and metal-dielectric layers and is based on the Smith-Purcell effect.

A theoretical study of the scattering of an obliquely incident magnetostatic forward volume wave (MSFVW) at a YIG-film edge is reported. The study takes into account the fields in the air region to the right of the scattering plane and all of the scattered MSFVW modes. The results are in general agreement with, but more accurate than, previous results that assumed the presence of the air fields (but only partially) and considered a single reflected MSFVW mode. The scattering problem is extended to a more accurate determination of the dispersion properties of the MSFVW width modes. >

In this work, we report on the experimental demonstration of magnetoquasistatic volume wave resonances in a 2-dimensional near field metamaterial (MM). Previous works have described only theoretically the magnetostatic waves in near field MMs and have reported peaks and valleys in the mutual coupling of MM enhanced wireless power transfer that they have attributed to Fabry-Perot resonances, however, neither has been experimentally measured nor characterized. We report on the direct magnetic field measurement of magnetostatic volume waves in a 2D near-field MM and show that the periodic peaks and valleys in mutual coupling observed previously are indeed due to a Fabry-Perot oscillation. In addition, we show that these resonances can be predicted from experimentally extracted permeability and the dimensions of the system.

The coupling of RF current in a strip transducer to magnetostatic forward volume wave modes in a one-port straight edge resonator is discussed in terms of input impedance. As results, the coupling strength is proportional to the operating frequency and some material parameters, such as saturation magnetization (Ms), YIG film thickness and the inversion of linewidth (//spl Delta/H). Further analyses demonstrate that changing the resonator dimensions along transducer linearly changes the coupling, but changing the length along the direction vertical to the transducer leads to an optimum coupling region. The comparison of the predictions with experiment results confirms the validity of the theory. >

A novel magnetooptic (MO) Bragg cell modulator that utilizes a magnetostatic forward volume wave (MSFVW) oscillator in a feedback loop is presented. The carrier frequency of the MSFVW signals involved in the MO interaction is tuned linearly from 2.112 to 3.274 GHz by increasing an external bias magnetic field from 2350 to 2900 Oe. Compared with a conventional MSFVW delay line-based MO Bragg cell modulator, the proposed modulator can provide significantly higher diffraction efficiency owing to reduction of insertion losses in the MSFVW oscillator.

The authors present a study of magnetostatic volume wave (MSVW) propagation in multilayered magnetic thin films with non-collinear magnetizations. YIG/GGG/YIG structure is used. The layered film is in the

An MSW (magnetostatic-wave) SER oscillator has been designed and characterized, exhibiting good performances for X-band applications. Acceptable Q/sub ext/ values (up to 3600), tunability, and good pushing characteristics have been obtained. The tunability performances have been extended between 7.5 GHz and 11 GHz by increasing the RF coupling factor and without comprising oscillator low noise characteristics, which is the correct tradeoff when high spectral purity and broadband tunability are both required. Output powers between +5 dBm and +15 dBm have been measured. >

A phenomenological unloaded Q‐factor (Qu) theory has been derived for all the three kinds of magnetostatic‐wave straight‐edge resonators (MSW‐SERs), i.e., forward volume wave (MSFVW), backward volume wave (MSBVW), and surface wave (MSSW). It turns out that the Qu values of MSW‐SERs are very close to that of the uniform precession mode with the exception of MSSW‐SERs and MSBVW‐SERs operating at frequencies below 3 GHz. The experimental responses on MSFVW‐SERs are in good agreement with those predicted by the present theory

A novel magnetooptic (MO) Bragg cell modulator that utilizes a magnetostatic forward volume wave (MSFVW) oscillator is presented. The carrier frequency of the MSFVW signals involved in the MO interaction is tuned linearly from 2.112 to 3.274 GHz by increasing an external bias magnetic field from 2350 to 2900 Oe. Compared with a conventional magnetostatic wave (MSW) delay line-based MO Bragg cell modulator, the proposed modulator can provide significantly higher diffraction efficiency owing to reduction of insertion losses in the MSFVW oscillator. Furthermore, the oscillator-type MO modulator can be more easily integrated with other MMIC devices.

Magnetostatic forward volume wave excitation by multi-element transducers are exactly analyzed by using the integral kernel expansion method. The dependence of excitation efficiency for each excited mode upon frequency and spacings and widths of strips is studied