**John Eichelberger**

International Arctic Research Center, University of Alaska Fairbanks, Fairbanks, AK 99775, USA<EMAIL_ADDRESS>
Received: 15 April 2020; Accepted: 25 May 2020; Published: 1 June 2020

**Abstract:** Proximity to magma bodies is generally acknowledged as providing the energy source for hot hydrothermal reservoirs. Hence, it is appropriate to think of a "magma–hydrothermal system" as an entity, rather than as separate systems. Repeated coring of Kilauea Iki lava lake on Kilauea Volcano, Hawaii, has provided evidence of an impermeable, conductive layer, or magma–hydrothermal boundary (MHB), between a hydrothermal system and molten rock. Crystallization on the lower face of the MHB and cracking by cooling on the upper face drive the zone downward while maintaining constant thickness, a Stefan problem of moving thermal boundaries with a phase change. Use of the observed thermal gradient in MHB of 84 ◦C/m yields a heat flux of 130 W/m2. Equating this with the heat flux produced by crystallization and cooling of molten lava successfully predicts the growth rate of lava lake crust of 2 m/a, which is faster than simple conduction where crust thickens at √ *t* and heat flux declines with 1/ √ *t*. However, a lava lake is not a magma chamber. Compared to erupted and degassed lava, magma at depth contains a significant amount of dissolved water that influences the magma's thermal, chemical, and mechanical behaviors. Also, a lava lake is rootless; it has no source of heat and mass, whereas there are probably few shallow, active magma bodies that are isolated from deeper sources. Drilling at Krafla Caldera, Iceland, showed the existence of a near-liquidus rhyolite magma body at 2.1 km depth capped by an MHB with a heat flux of ≥16 W/m2. This would predict a crystallization rate of 0.6 m/a, yet no evidence of crystallization and the development of a mush zone at the base of MHB is observed. Instead, the lower face of MHB is undergoing partial melting. The explanation would appear to lie in vigorous convection of the hot rhyolite magma, delivering both heat and H2O but not crystals to its ceiling. This challenges existing concepts of magma chambers and has important implications for use of magma as the ultimate geothermal power source. It also illuminates the possibility of directly monitoring magma beneath active volcanoes for eruption forecasting.

**Keywords:** magma energy; magma convection; hydrothermal system; heat flux; geothermal energy; eruption


3.5.1. Aromatic Structures

According to Section 2.2, the XBP of gas coal in this study was 0.407, which was close to the XBP values of phenanthrene and anthracene in the literature [21]. According to the conclusion of the molecular structure in the literature [11], the macromolecular structure was dominated by anthracene and phenanthrene, followed by the pyrene and naphthalene rings. The bridging carbon ratio was made close to the calculated value by adjusting the numbers of various aromatic rings. The types and numbers of aromatic structures in the molecular structure are shown in Table 5.

#### 3.5.2. Aliphatic Carbon Structures

The aliphatic carbon in coal mainly exists in the form of branched chain, linked aromatic rings, aliphatic rings, side chains, and bridging carbons [29]. Based on the aromatic carbon ratio, the number of aromatic carbon atoms, and Table 5, the total and aliphatic carbon atoms were calculated to be 181 and 21, respectively. From the abovementioned data, the number of hydrogen atoms in gas coal was calculated to be 150. The proportions of fa1H, fa1\*, and fa10 in gas coal were 6.5%, 4.6%, and 0.9%, respectively. Therefore, the aliphatic carbon atoms in gas coal mostly existed in the forms of methyl, methylene, hypo methyl, and quaternary carbon, and the oxygen-linked lipid carbon was the least abundant.

**Table 5.** The types and numbers of aromatic structures in gas coal.

#### 3.5.3. Heteroatom Structures

The numbers of oxygen and nitrogen atoms in gas coal were calculated to be 9 and 3, respectively, by the total number of carbon atoms and the atomic ratio. According to XPS analysis, oxygen atoms in gas coal existed in the forms of five ether oxygen bonds, two carbonyl groups, and one carboxyl group. The nitrogen atoms existed in the form of two pyridine nitrogen and one pyrrole nitrogen.


**5. Equity in health care financing**

Equity has been one of the important variables in health care systems, but inequities in health care financing and access are still very pervasive. Ample evidence suggests that the poor have less access to health care and suffer more devasting consequences of morbidity and mortality than the rich. The poor have lower levels of health care utilization than the rich, though they have more health needs and spend more on health care as percentage of their income than the wealthy individuals [17].

In this section, equity is contextualized as equity in access to health insurance, health care, and equity in health care delivery: distribution of health care services, urban-rural dichotomy, and ethnic minority communities. The Nobel Prize winner Amartya Sen [18] argues that health is one of the most important variables of human life and an important constituent of human capability, but the pervasiveness of inequalities in health care access and delivery is more disturbing than any other sectors.

Equity in health means that ideally everyone should have a fair opportunity to invest in their health to attain full health potential without any one being disadvantaged from achieving this potential if it can be avoided [19]. Equity can, thus, be explained as an ethical concept which is grounded in the principles of distributive social justice. Regrettably, different people and different authorities tend to interpret equity in diverse ways. To counterbalance the open interpretation of equity and create an operational concept, Braverman and Gruskin [20] defined equity (in health) as "the absence of socially unjust or unfair health disparities, the absence of systematic disparities in health (or in the major social determinants of health) between social groups who have different levels of underlying social advantage/disadvantage." This definition reminds us that the society is composed by diverse groups of people with different capabilities, sexual orientation, and different wealth gradients with unique needs in various locations. We call for a society where both the haves and the have-nots have equitable health insurance and universal health coverage without discrimination.

Based on the experts' definitions and Rawls' theory of justice, I conceptualize equity in this paper, as fairness in financial contribution (premium payment), fairness in health insurance coverage and access to health care, fairness in health care delivery, and fairness in the determination of benefits package. For example, the premiums of health insurance should be based on individuals or households' ability to pay. The wealthy individuals or households should pay more, according to some progressive principle while poor pay less, and indigents should be covered by safety net insurance.

*Health Insurance for Economically Disadvantaged People in LMICs: What are the Best Options? DOI: http://dx.doi.org/10.5772/intechopen.105679*


3.1.2. Structure

Freeze-dried purees showed high porosity, typical of freeze-dried products, with values ranging from 86.4–87.4%. The PLS–R indicated a correlation between FR-S and porosity (mainly projected in the positive side of axis 2, Figure 1), which means that a slow rate of freezing leads to bigger ice crystals and so a bigger expansion of gas cells in the structure (higher porosity) during the freeze-drying process. Nevertheless, they are in the inner circle, which means the effect is not significant. In fact, according to ANOVA, porosity of the samples was not significantly affected by any factor evaluated (*p* > 0.05).

As a result of the mechanical analysis, the force versus distance curves were obtained for each sample freeze-dried under each of the 12 conditions (Figure 3). The linear regression of the first part of the curve was taken to calculate the slope before Ff, related to the rigidity of the sample. As can be observed in the PLS-R (Figure 1), factors T50 and rigidity are both partially correlated and projected on the negative side of axis 2, which means that a higher temperature leads to an increase in the rigidity of the freeze-dried samples. However, because the rigidity is projected in the inner circle, it indicates a moderate positive correlation. In regards to the ANOVA results, the shelf temperature had a significant effect on the rigidity (slope) of the freeze-dried samples (*p* < 0.05); however, its low F-Value (8.65) makes it possible to confirm its low significance.

**Figure 3.** Examples of force–distance curves obtained from the freeze-dried purees frozen at a slow rate and freeze-dried at 5 Pa, and with different shelf temperatures (30, 40 and 50 ◦C). Ff: fracture force.

Values of the slope 18–26 N/mm were obtained when heating the freeze-drier shelves to 50 ◦C, as compared to 11–18 N/mm values obtained at 30 and 40 ◦C. As a greater slope indicates less deformation of the sample by exerting an effort on it, it can be concluded that freeze-drying heating the shelves to 50 ◦C promotes the mechanical rigidity of the freeze-dried samples before they fracture. This can be considered desirable as it would be related to a higher mechanical resistance of the sample during its handling before consumption.

Fracture force of all the samples varied between 12.1 ± 1.6 N and 19 ± 5 N. The PLS-R revealed a moderate positive correlation between fracture force and both lower pressure (P5) (both projected in the positive side of axis 1) and T50 (both projected in the negative side of axis 2). This means that working with lower pressure and higher temperature seems to promote a freeze-dried puree that is more resistant to fracture. According to the ANOVA, neither the temperature nor the freezing rate showed a significant effect on the fracture force (*p* > 0.05). The pressure did show *p* < 0.05, but again, with a very low *F*-Value (7.17).

The water content of the samples ranged between 2.2 ± 0.3 and 4.2 ± 0.2 g water/100 g sample. The PLS-R indicated a high correlation between water content (%), high pressure (P100) and low temperature (T30), circled in blue colour in Figure 1. In fact, this statement was confirmed by the ANOVA that indicated a significant effect on the final water content of the freeze-dried samples by the shelf temperature and the pressure (*p* < 0.05). In this way, drying at the highest pressure (100 Pa) and the lowest shelf temperature (30 ◦C) promoted samples with the highest water content. On the other hand, Figure 1 shows a clear negative correlation between water content and fracture force, which means the smaller the water content of the freeze-dried samples, the greater the mechanical resistance to fracture. In this case, the final water content of the samples was lower than 4.2%. However, it seems that small changes outside this range, related to working conditions, will have an important impact on the mechanical properties of the sample.


**2.3 SRS in random laser**

Multiple scattering is a well-known phenomenon, occurring in nearly all optical opaque materials. Random walk of light waves in disordered materials could carry out to a multiple scattering with a consequent strong localization of electric field. Wave character of multiply scattered light is not lost and the wave can interfere both during and after the scattering process. Considering that the scattering is elastic, optical information does not change. Furthermore, due to reciprocity, multiple scattering is, in theory, fully reversible [2]. Reciprocity means that waves following the same path in opposite directions can interfere. Interference between such counter-propagating waves is always constructive, which gives rise to the incredibly robust interference phenomenon of coherent backscattering (also called weak localization). The combination of weak localization together with reciprocity, leads to a series of interesting physical effects and to an enormous potential for new disorder-based optical applications [14].

The first experimental evidence of lasing via a Raman interaction in a bulk three-dimensional random medium was demonstrated taking advantage of barium sulfate (BaSO4) powder with particle diameters of 1–5 μm. The pump energy threshold was 1.05 mJ; at higher values, gain is stronger than losses and SRS dominates the conversion process, allowing to obtain random Raman lasing. A Raman signal of 2.0 mJ was measured at a maximum of 11.5 mJ of pump energy [2, 15]. The complicated dynamics of nonlinear pulse propagation in a turbid medium make a theoretical approach to describing this problem very challenging.