**Abstract**

The coronavirus disease caused by the SARS-CoV-2 virus (COVID-19) pandemic has changed not only global epidemiological and economic developments but also the lives of every individual, with particular severity for patients. The number of acute illness cases grew rapidly, significantly increasing the workload of hospitals, and simultaneously, new chronic diseases emerged, such as persistent post-COVID-19 syndrome (PPCS), with unclear etiology, symptoms, and complexity—similar to myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Accordingly, the burden of chronic diseases poses new long-term challenges for primary healthcare and requires new approaches to patient care. This chapter provides insight into the integrative approach to healthcare and focuses on potentially new solutions by implementing an integrative attitude to the treatment of post-COVID-19 and ME/CFS patients in primary healthcare. Integrative health coaching contributes the holistic approach to patients' overall health and resilience through cognitive practice and patient active engagement. The findings of this chapter can enrich the personcentered approach and healthcare system strengthening through holistic measures and systems thinking.

**Keywords:** persistent post-COVID-19 syndrome (PPCS), myalgic encephalomyelitis/ chronic fatigue syndrome (ME/CFS), integrative approach, coaching, patient-reported outcomes (PROs)


**1.2. Customer problem**

#### *1.2.1. Automotive*

The new fuel economy standards which mandate an average fuel economy of 54.5 miles per gallon for the 2025 model year will highly motivate auto manufacturers to step up development of improved vehicle designs and technologies to sharply improve the fleet mileage. Mass produced models will need to utilize more efficient engines and new lighter but safe car bodies. Automobile manufacturers have investigated alternatives to the steel traditionally used in car production. However, in most cases, the on-road properties of steel make it the best choice for automotive fabrication [3]. As a result, we are seeing a renewed interest in the use of high-strength steel and composites.

Carbon-fiber composite car structures are now in vogue. BMW produces two all carbon electric vehicle designs the i3 and the i8. General Motors' Corvette Stingray has a carbon-fiber roof and hood. Other recent autos that feature carbon-fiber-reinforced polymer (CFRP) components include the Audi R8, the BMW M6, and the Dodge Viper. Most of these models, however, are high end, low-volume vehicles that are mainly assembled manually because composites use in low and medium-priced cars is still awaiting the development of cost effective massproduction processes and materials [4, 5].


We chose November 9, 2004 for analysis. On this day, we observed a complicated geomagnetic disturbance of the ionosphere caused by the solar flares of November 3 (01.24-01.44 UT) and November 5 (11.26-11.41 UT). On November 7, 2004, an abrupt drop in dynamics of the horizontal component H of the geomagnetic field was recorded at 22.00-24.00 UT. On No‐ vember 9, 2004, moderate disturbances of the geomagnetic field were observed. In the time interval 20.00- 21.00 UT, there was a strong disturbance of the geomagnetic field once again; it was caused by the solar flare of November 5, 2004. Consequently, the day we analysed is characterised by a whole gamut of perturbing factors which affected near-Earth space and positioning accuracy.

There was increase in ED in the F layer from 14.00 to 20.00 UT on November 9, 2004. On the next day, however, such ED disturbances were not observed. The main contribution to ionospheric scintillations is made by disturbances in the F region. Consequently, we may assume that there were favourable conditions for formation of such scintillations on November 9.

The decrease in the average (of all satellites under observation) signal level at the receiving point can serve as a manifestation of intense ionospheric scintillations. To prove this, we analysed series of measurements of the SV signal-to-noise for each hour of observation. In

**Figure 15.** Averaged values of the SV signal level with elevation angles θ of more than 60° on November 9, 2004.

order to provide reliable detection of the effect, we considered measurements for which elevation angle θ was more than 60°. Because of this, the strength of effects at low elevation angles (whereat the signal attenuation can be related not only to ionospheric disturbances) decreases.

Results are presented in Fig. 15. SN1 (a) is signal-to-noise at L1 and SN2 (b) is the same at L2. From 4.30 to 9.50 UT, there were no SV with elevation angles θ of more than 60° over the observation site. A steady decrease in the signal level of both operating frequencies of SV is observed at the observation site from 17.00 to 21.00 UT. It coincides in time with occurrence of intense ionospheric disturbances caused by the magnetic storm.

The decrease in signal-to-noise ratio at the receiving point due to ionospheric scintillations may lead to deterioration in positioning quality. Fig. 16a presents series of errors in the positioning of ISTP - *ΔS* = *ΔX* 2 + *ΔY* 2 + *ΔZ* 2 . Measurements were made with MRK-19L, on the basis of GPS data only. The time step was 4 s. A sharp increase in positioning errors was observed from 15.00 to 20.30 UT. This period corresponds to the local night (23.00-04.30 LT) and is marked by rectangle in Fig. 16a.

Notice that the said deterioration in the positioning precision correlates well (according to the occurrence time) with appearance of regions with increased ED. Besides, the period of increase in positioning errors coincides with the period of decrease in the SV signal level at both GPS frequencies (Fig. 15).

To extract effects caused by deterioration in geometry of constellation of satellites, we calcu‐ lated Position Dilution of Precision (PDOP). Fig. 16b presents PDOP values for ISTP. The time step was 4 s. The maximum PDOP values were observed at 01.10 and 02.20 UT. This was due to the local peculiarity of the observation site. Note that the increase in positioning errors did not coincide with the maximum PDOP values. From 15.00 to 20.30 UT, we observed only shortterm increases (> 3.5) in PDOP values. Thus, ionospheric scintillations of the SV signal amplitude were most likely to make the most substantial contribution to the increase in positioning errors during the period under consideration.

Fig. 17 exemplifies TEC observations made by GPS satellites PRN 06 and PRN 20 on November 9, 2004 at 00.00-03.00 UT. The figures also present the S4 index dynamics (see Fig. 17c,f). Time

order to provide reliable detection of the effect, we considered measurements for which elevation angle θ was more than 60°. Because of this, the strength of effects at low elevation angles (whereat the signal attenuation can be related not only to ionospheric disturbances)

**Figure 15.** Averaged values of the SV signal level with elevation angles θ of more than 60° on November 9, 2004.

Results are presented in Fig. 15. SN1 (a) is signal-to-noise at L1 and SN2 (b) is the same at L2. From 4.30 to 9.50 UT, there were no SV with elevation angles θ of more than 60° over the observation site. A steady decrease in the signal level of both operating frequencies of SV is observed at the observation site from 17.00 to 21.00 UT. It coincides in time with occurrence

The decrease in signal-to-noise ratio at the receiving point due to ionospheric scintillations may lead to deterioration in positioning quality. Fig. 16a presents series of errors in the

the basis of GPS data only. The time step was 4 s. A sharp increase in positioning errors was observed from 15.00 to 20.30 UT. This period corresponds to the local night (23.00-04.30 LT)

Notice that the said deterioration in the positioning precision correlates well (according to the occurrence time) with appearance of regions with increased ED. Besides, the period of increase in positioning errors coincides with the period of decrease in the SV signal level at both GPS

To extract effects caused by deterioration in geometry of constellation of satellites, we calcu‐ lated Position Dilution of Precision (PDOP). Fig. 16b presents PDOP values for ISTP. The time step was 4 s. The maximum PDOP values were observed at 01.10 and 02.20 UT. This was due to the local peculiarity of the observation site. Note that the increase in positioning errors did not coincide with the maximum PDOP values. From 15.00 to 20.30 UT, we observed only shortterm increases (> 3.5) in PDOP values. Thus, ionospheric scintillations of the SV signal amplitude were most likely to make the most substantial contribution to the increase in

Fig. 17 exemplifies TEC observations made by GPS satellites PRN 06 and PRN 20 on November 9, 2004 at 00.00-03.00 UT. The figures also present the S4 index dynamics (see Fig. 17c,f). Time

. Measurements were made with MRK-19L, on

of intense ionospheric disturbances caused by the magnetic storm.

positioning of ISTP - *ΔS* = *ΔX* 2 + *ΔY* 2 + *ΔZ* 2

214 Geodetic Sciences - Observations, Modeling and Applications

positioning errors during the period under consideration.

and is marked by rectangle in Fig. 16a.

frequencies (Fig. 15).

decreases.

**Figure 16.** Positioning errors (a) and Position Dilution of Precision (b) during the magnetic storm on November 9, 2004. Data from MRK-19L were used for positioning.

series of TEC variations with eliminated trend are given in Fig. 17a,d. The method to eliminate the trend is described in (Afraimovich and Perevalova, 2006). We calculated TEC values with the use of two-frequency phase measurements. The values were measured with ASHTECH Z-XII3T (IRKT). The time step was 30 s. Fig. 17b,e illustrate series of the time derivative of TEC. The scintillation index was calculated using MRK-19L measurements of signal-to-noise ratio at the GPS L1 frequency.

$$\mathbf{S4}^2 = \frac{\left[\left\{\mathbb{P}^2\right\} - \left\{\mathbb{P}\right\}^2\right]}{\left\{\mathbb{P}\right\}^2},\tag{24}$$

where *Р* is the current value of signal-to-noise ratio measured in relative units and the time step is 4 s. When calculating the scintillation index, averaging of measurements of signal *Р* amplitude was made in the time interval of 28 s in order to coordinate TEC measurements and estimate S4 values in time.

According to Fig. 17a-c, short-period TEC disturbances corresponding to small-scale ED irregularities are quite insignificant in this case. Smooth TEC variations are more significant. This is also the case for small values of the S4 index (S4≤0.1).

Fig. 17d-f presents data from GPS PRN 06. As can be seen, fast TEC variations caused by smallscale ED irregularities are dominant. Consequently, high values of the S4 index (*≥*0.8) are observed (Fig. 17 f). We can draw a conclusion that, in the conditions under consideration, the S4 index reflects disturbances of propagation medium of SV signals quite reliably. The analysis substantiates the validity of using the S4 index under disturbed geomagnetic conditions. In this case, we observed superposition of effects of several geomagnetic disturbances of radio wave propagation medium. Thus, the S4 index can be applied to making online control of the quality of measurements of radio navigation parameters during magnetic storms.

There are, however, a number of restrictions that have not been taken into consideration. These restrictions should be considered individually. Noteworthy is the fact that velocity v and integration time of the right-hand and left-hand sides of equation (23) are undetermined parameters. These parameters may reliably reflect the current conditions of radio wave propagation.

**Figure 17.** TEC variations (a, d), TEC derivative (b, e), and the S4 index (c, f). Data from the GPS satellite PRN 20 (a-c) and PRN 06 (d-e) were used.

The article deals mainly with ionospheric scintillations caused by the SV signal diffraction. The main contribution is made by ED irregularities with the scale of about the first Fresnel zone *dF* ≈ 2*λ* ⋅ *z*. In this case, the integration time can be determined from relative velocity v. The Fresnel frequency *vF* (related to velocity *v*) corresponds to the magnitude inversely propor‐ tional to the characteristic scintillation period.

substantiates the validity of using the S4 index under disturbed geomagnetic conditions. In this case, we observed superposition of effects of several geomagnetic disturbances of radio wave propagation medium. Thus, the S4 index can be applied to making online control of the

There are, however, a number of restrictions that have not been taken into consideration. These restrictions should be considered individually. Noteworthy is the fact that velocity v and integration time of the right-hand and left-hand sides of equation (23) are undetermined parameters. These parameters may reliably reflect the current conditions of radio wave

**Figure 17.** TEC variations (a, d), TEC derivative (b, e), and the S4 index (c, f). Data from the GPS satellite PRN 20 (a-c)

The article deals mainly with ionospheric scintillations caused by the SV signal diffraction. The main contribution is made by ED irregularities with the scale of about the first Fresnel zone *dF* ≈ 2*λ* ⋅ *z*. In this case, the integration time can be determined from relative velocity v. The

quality of measurements of radio navigation parameters during magnetic storms.

propagation.

216 Geodetic Sciences - Observations, Modeling and Applications

and PRN 06 (d-e) were used.

$$
\upsilon\_{\text{f}} = \frac{\upsilon}{\sqrt{2\lambda \cdot z}}\tag{25}
$$

However, it is a common knowledge that the Fresnel frequency can vary over a wide range. For operating GPS frequencies, typical sizes of inhomogeneities located at 110-400 km that make the main contribution to amplitude scintillations are in the range 145 to 310 m. The GPS satellite moves in a circular orbit at 20200 km. The revolution period is 12 hours. If the line of sight is zenith-directed, the horizontal component of the rate of motion of the SV signal trajectory is 21 m/s for the E region and 77 m/s for the F region. The horizontal drift velocity of small-scale ED irregularities in middle latitudes is usually more than 150 m/s (Afraimovich et al., 2004). Consequently, the Fresnel frequency value can vary from 0.08 to 0.36 Hz. In high latitudes, the drift velocity can be up to 1 km/s. In this case, the Fresnel frequency can be significantly higher (Bhattacharyya et al., 2000; Afraimovich et al., 2004). Consequently, we should also analyse time of averaging of observational data that enter into the left-hand and right-hand sides of equation (23) to estimate adequately the current conditions of scintillation formation.

The restriction can be insignificant, if the phase-screen approximation is adequate. According to (Bhattacharyya et al., 2000), equation (23) can be replaced by the following empirical expressions:

$$\begin{aligned} DROTI &= \alpha \cdot v\_{\text{f}} \cdot \text{S4} \\ DROTI &= \sqrt{\left\langle \left(\frac{d^2}{dt^2} \Delta I(t)\right)^2 \right\rangle - \left\langle \frac{d^2}{dt^2} \Delta I(t) \right\rangle^2} \\ &\quad \cdot \text{DRO} = \text{ROTI} \end{aligned} \tag{26}$$

where *α* is the empirical parameter chosen for current observational conditions. In (Bhatta‐ charyya et al., 2000, Bhattacharyya, 1999), it was found that *α* =1.6⋅103 −8.5⋅103 .

The phase screen approximation is not applicable when waves pass through the layer of inhomogeneities having high intensity and thickness. This is the case for the low-latitude and equatorial ionosphere. In the case under consideration, we have observed saturation of amplitude scintillations. If the irregular layer is thick, amplitude fluctuations are developed inside of it. As a result, the wave becomes subject to both phase and amplitude disturbances in the ionospheric layer output (Yeh and Liu, 1982). The well-known observational results show that amplitude scintillations were usually registered in such cases. Scintillations of the phase, angle of arrival and polarisation of received radio emission were observed much less often (Gunze, 1982). In this case, the S4 index determined only intensity of amplitude scintil‐ lations. These data are not enough to give immediate notice to GNSS consumers of a sharp deterioration in conditions of radio wave propagation. There are known cases of tracking loss of SV signals due to abrupt changes in the carrier phase. Noteworthy is the fact that variations in the signal amplitude are relatively low (Afraimovich et al., 2009b).

Additional research is needed to find new indices of signal propagation medium under different conditions. These indices should reflect variations in other parameters of the SV signal. The analysis should include influence of fluctuations of different radio-signal param‐ eters on stability of system operation.

### **Acknowledgements**

The authors are grateful a lot to Prof. E.L. Afraimovich, who will never see this text, sad to say. These results couldn't be obtained without him. Authors express profound gratitude to Prof. G. Y. Smolkov for his support and interest in this investigation. We are thankful to N.S. Gavriluk, A.B. Ishin, Prof. M.V. Tinin for their assistance in the preparing some parts. We are obliged to Dr. V. V. Grechnev for his help in using the 1 GHz and 2 GHz data of the Nobeyama Radio Polarimeters and colleagues from the Nobeyama Radio Observatory for solar radio emission data on December 13, 2006, as well as the International GNSS service and Geograph‐ ical Survey Institute of Japan for RINEX data. The study was partially supported by RFBR (under grant No. 12-05-33032 а), by the Ministry of Education and Science of the Russian Federation (under agreement Nos. 8699, 8388, and 14.518.11.7065) and the Russian Federation President Grant MK-2194.2011.5.

### **Author details**

Vladislav V. Demyanov1\*, Yury V. Yasyukevich2 and Shuanggen Jin3

\*Address all correspondence to<EMAIL_ADDRESS>
1 Irkutsk State Railway University, Russia

2 Institute of Solar-Terrestrial Physics, the Russian Academy of Sciences, the Siberian Branch, Irkutsk, Russia

3 Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai, China

### **References**

[1] Afraimovich, E. L. (2000). GPS global detection of the ionospheric response to solar flares // Radio Sci., N 6, , 35, 1417-1424.

[2] Afraimovich, E. L, & Perevalova, N. P. (2006). GPS monitoring of the Earth's upper atmosphere. Irkutsk. in Russian)., 480.

deterioration in conditions of radio wave propagation. There are known cases of tracking loss of SV signals due to abrupt changes in the carrier phase. Noteworthy is the fact that variations

Additional research is needed to find new indices of signal propagation medium under different conditions. These indices should reflect variations in other parameters of the SV signal. The analysis should include influence of fluctuations of different radio-signal param‐

The authors are grateful a lot to Prof. E.L. Afraimovich, who will never see this text, sad to say. These results couldn't be obtained without him. Authors express profound gratitude to Prof. G. Y. Smolkov for his support and interest in this investigation. We are thankful to N.S. Gavriluk, A.B. Ishin, Prof. M.V. Tinin for their assistance in the preparing some parts. We are obliged to Dr. V. V. Grechnev for his help in using the 1 GHz and 2 GHz data of the Nobeyama Radio Polarimeters and colleagues from the Nobeyama Radio Observatory for solar radio emission data on December 13, 2006, as well as the International GNSS service and Geograph‐ ical Survey Institute of Japan for RINEX data. The study was partially supported by RFBR (under grant No. 12-05-33032 а), by the Ministry of Education and Science of the Russian Federation (under agreement Nos. 8699, 8388, and 14.518.11.7065) and the Russian Federation

2 Institute of Solar-Terrestrial Physics, the Russian Academy of Sciences, the Siberian

[1] Afraimovich, E. L. (2000). GPS global detection of the ionospheric response to solar

3 Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai, China

and Shuanggen Jin3

in the signal amplitude are relatively low (Afraimovich et al., 2009b).

eters on stability of system operation.

218 Geodetic Sciences - Observations, Modeling and Applications

**Acknowledgements**

President Grant MK-2194.2011.5.

Vladislav V. Demyanov1\*, Yury V. Yasyukevich2

1 Irkutsk State Railway University, Russia

\*Address all correspondence to<EMAIL_ADDRESS>
flares // Radio Sci., N 6, , 35, 1417-1424.

**Author details**

Branch, Irkutsk, Russia

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**Author details**

Dmitry Lozhkin Russian Federal Research Institute of Fisheries and Oceanography, Sakhalin branch, Yuzhno-Sakhalinsk, Russian Federation

\*Address all correspondence to<EMAIL_ADDRESS>
© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

*Analysis of Spatiotemporal Variability of Surface Temperature of Okhotsk Sea and Adjacent… DOI: http://dx.doi.org/10.5772/intechopen.94918*


**2. General description of the device**

In order to provide the best fabrication tolerance, we base our design on an adiabatic taper (instead of, e.g., a resonant coupler that would provide a shorter transfer length). Before detailing the device, we single out here some points critical to its operation. These aspects dictate design choices for the rest of the device.

The first "hard point" is spectral stability. To achieve a lower OPO threshold, we choose a doubly resonant OPO (DR-OPO) configuration. Concerning the laser, to avoid mode competition and instability, the pump should not return into the laser cavity after having explored the OPO region. This requires DBR with

**111**

**2.2 Proposed design**

*Widely Tunable Quantum-Well Laser: OPO Diode Around 2 μm Based on a Coupled Waveguide…*

high reflectivities at signal/idler wavelengths and low reflectivities at the pump wavelength, as present, for example, in [6]. Furthermore, stability of the device is improved by in situ control of the phase mismatch, through shift of the pump wavelength or of the OPO cavity temperature. These two factors can be tuned independently if the laser and OPO temperatures are set separately. This is possible if the two areas are separated by at least 100 μm and are controlled by individual heaters. Thermal behavior and contact geometry are also expected to be critical. III/V on Si laser typically emits powers in the 10 mW range [11], while the pump power for OPO threshold is a few tens of mW in our case. The laser should be single mode for stable OPO operation, which imposes a maximal ridge width and thus a minimum optical power density. Furthermore, high-power single-mode lasers are usually shallowly etched (for single-mode operation) and mounted epi-down to limit thermal resistance [12]. In our case, these two aspects cannot be implemented at the same time. Indeed, if the laser is grown on top, the insulating section between laser and doped substrate makes it necessary to use lateral contacts, which requires deep lateral etching and compromises laterally monomode operation. On the opposite, if the laser is grown under the nonlinear (NL)

waveguide, shallow etches are possible but epi-down mounting is impossible.

conversion and assess their impact on conversion efficiency.

etry for its compatibility with effective indices in our project.

mode operation can then be achieved with a contact on one side.

**2.1 Choice of geometry**

called "NL waveguide" (for nonlinear).

We also carefully examine fabrication tolerances in the region of parametric

To reduce fabrication complexity, we limit ourselves to a single level of etching. This implies that the bottom waveguide geometry is invariant in the direction of propagation and that the top waveguide is narrowed. Keeping in mind the points presented in the previous section, we summarize the advantages of different geometries in **Table 1**. The waveguide where parametric light conversion takes places is

We explore the range of possibilities opened by the GaAs/AlAs/InAs system, and we base the design of the laser part on already-existing, high-performance AlGaAs lasers at 1 μm [13]. The detail of layer's thickness and composition is not shown here for confidentiality reasons. In this structure, the fundamental mode at 0.98 μm has an effective index of about 3.36. Regarding the waveguide where parametric conversion is to take place, modal phase matching is more readily achieved if the pump mode is of order 2 in the vertical direction. Additionally, high conversion efficiency is favored by high cladding/core index contrasts. This, coupled with the fact that we have to work with a higher order mode, sets the maximum value of effective index in the waveguide at approximately 3.2. We therefore choose the "laser on top" geom-

This choice has two important consequences. To keep the underlying waveguide undoped, contact for the bottom part of the laser must be taken laterally instead of under the substrate. This implies that the gain region should be deeply etched to clear access to the contacts. This is obviously at odds with a single-mode laser operation, since the important index contrast between air and semiconductor (in the absence of a regrowth step) will cause the laser to oscillate on several transverse modes, unless it is extremely narrow, which is not desirable given the target optical power. As a solution, we propose to etch deeply only one side of the ridge. Single-

Given the constraints presented earlier, we propose a general design. A general view of the structure is shown in **Figure 1**. On the left, we choose a DFB cavity for the

*DOI: http://dx.doi.org/ 10.5772/intechopen.80517*