**3.1 Solvent dependence of TPP**

It has been reported in literature that the measured absorption spectra of the TPP considerably depend on the dielectric constant of the solvent. For instance, the experimentally measured absorption spectrum the TPP exhibited the Soret-band at 398 nm in a pulsed supersonic expansion of helium [50], which is considerably shifted to 420 nm in toluene (ε = 2.374) [51], 419 nm in benzene (ε = 2.271) [52], 417 nm in *tetrahydrofuran* (ε = 7.426) and 415 nm in acetone (ε = 20.493) [51]. The Q(0-0) bands have been measured at 529 and 640 nm in a pulsed supersonic expansion of helium [50], which are also significantly shifted to 548 and 647 nm in benzene [52]. Furthermore, the lowest triplet state (T1) of TPP at 77 K in methylcyclohexane [53] and diethyl ether/petroleum ether/isopropyl alcohol (in the ratio of 5/5/2) [54] was observed at 865 nm and 859 nm, respectively. The triplet-triplet absorption transitions of TPP in toluene were experimentally observed at 780, 690, 430, 405 and 390 nm [55].

It is worthy to note that the geometric structures of the TPP molecule both in the ground state and the lowest triplet state belong to the C2v symmetry point group. The calculated solvent effect on the electronic spectrum of the TPP are summarized below.

*Density Functional Theory Study of the Solvent Effects on Electronic Transition Energies… DOI: http://dx.doi.org/10.5772/intechopen.99613*

**Singlet TPP: Figure 1A** provides the calculated absorption spectra of FBP in the different solutions used. The shifts in spectral positions of the Q, B (Soret) and L bands caused by the solvent are given in **Figure 1B** as functions of the dielectric constant of the solvent (ε).

The calculations indicate that the solvent effect on the Q1 and Q2 bands of the TPP are inconsequential. For instance, the Q1 band at 17398 cm−1 (574.8 nm) and Q2-band at 18566 cm−1 (538.6 nm) in gas-phase spectrum are 40 and 90 cm−1 red shifted to 17358 (576 nm) and 18473 cm−1 (541.4 nm), respectively, with increase in ε from 1.00 to 5.32; which then increased and become almost constant at around 17384 and 18506 cm−1 for ε > 20.493. However, the dependence of the calculated Soret bands (B1 and B2-bands) of the TPP significantly depend on solvent polarity. For example the B1 band at 25405 cm−1 (393.6 nm) and B2 band 26271 cm−1 (380.6 nm) in the gas phase spectrum initially decreased to 23890 (418.6 nm) and 24160 cm−1 (414.4 nm), respectively, with increase of ε from 1 to 5.32, and then blue-shifted to 23890 cm−1 (418.6 nm) and 24131 cm−1 (414.4 nm), respectively, for ε = 20.493 (acetone). With further increase in the dielectric constant (ε > 20.493), these bands positions become nearly stable at around 24574 (406.9, B1) and 24919 cm−1 (401.3 nm, B2) within 120 cm−1 fluctuations.

Similar to the modification in the positions of the B-bands, the spectral position of the L-band at 28862 cm−1 (346.5 nm) in the gas-phase (ε = 1.00) is first red-shifted to 28212 cm−1 (354.5 nm) in region of ε = 1 to 5.324, then blue-shifted to 29067 cm−1 (334 nm) for ε = 20.493, and then remains unchanged at 28334 cm−1 (352.9 nm) within ±20 cm−1 variation with the further increase in ε (**Figure 1**).

**Triplet TPP:** The lowest triplet state T1 of the TPP in both gas-phase and solvent phase was estimated from calculated global energy difference between the singlet ground state and the lowest triplet state, i.e., E(T1) = E(the global energy of the lowest triplet state)- E(the global energy of the ground state). The energy level of the T1 state of the TPP in the gas phase lies about 11406 cm−1 (876.8 nm) above the ground state energy (S0). The estimated solvent effect on the energy gap between S0-T1 states is inconsequential, only about 20 cm−1 red-shifted with increasing solvent polarity (see **Figure 2B**).

The calculated triplet-triplet electronic transitions up to 25000 cm−1 (400 nm) are given in **Figure 2(A** and **B)**. The calculations indicate that the triplet states

#### **Figure 1.**

*(A) The calculated solvent-dependence of the singlet-singlet electronic absorption spectrum of the TPP in the thirty-nine different environments, where the dielectric constant of the molecular environment increases from bottom (*ε *= 1.00) to top (*ε *= 181.560); (B): The shift in the positions of the Q1, Q2, B1, B2 and L1 bands reference to their corresponding values in gas-phase spectrum as function of dielectric constant of the solvent (*ε*).*

**Figure 2.**

*(A) The calculated solvent-dependence of the triplet-triplet electronic absorption spectrum of the TPP in the thirty-nine different environments, where the dielectric constant of the molecular environment increases from bottom (*ε *= 1.00) to top (*ε *= 181.560); (B): The shift in the energy level of the Tn state reference to their corresponding value in gas-phase spectrum as function of dielectric constant of the solvent (*ε*). The shift in the energy level of the T1 state:* Δ*E(T1,*ε*) = E(T1,*ε*)-E(S0,*ε*).*

at 18805 cm−1 (531.8 nm; labeled as T10) and 20722 cm−1 (482.6 nm, T13) in the gas-phase spectrum of the TPP are gradually red-shifted to 18232 and 20041 cm−1 (or 548.5 and 499.0 nm) as a function of ε up to 28.29), respectively, and become stable within a few wavenumbers variation with the further increment in solvent dielectric constant (ε). On contrary to red-shifts in the energy level of the T10 and T13 states, the T21 (at 22130 cm−1/451.9 nm) and T25 (22926 cm−1/436.2 nm) in the gas-phase are blue-shift to 22666 cm−1 (441.2 nm) and 23849 cm−1 (419.3 nm), respectively, as function of ε up to 28.29. Additionally, the solvent leads to blue shifts (around 400 cm−1) and red shifts (about 200 cm−1) in the calculated energy levels of other triplet states as seen in see **Figure 2B**.

The İntersystem crossing (ISC) between singlet and triplet excited states of a molecular system is very important for many purposes in photochemistry. Therefore, we also investigated solvent effect on the energy barrier between singlet and triplet state, ΔE(ISC) = E(triplet)-E(singlet), where the ISC may take place.

The results from calculations show that the energy gap between Q2-band and T3 triplet state regularly decreases to −4 cm−1 (ε = 10.125) from −330 cm−1 (in gas-phase) with increasing solvent polarity and then slowly increases up to 60 cm−1 with the increase solvent polarity up to ε = 78.355. The gap between B2 band and T4 triplet state rapidly decreases from −972 cm−1 in the gas phase to −84 cm−1 in Xenon (ε = 1.706), increases from 132 cm−1 (ε = 1.911) to a maximum value of 972 cm−1 (ε = 5.32), then follow an exponentially decrease to 110 cm−1 (ε = 78.355). The triplet state T7 lies about 191 cm−1 above the L1-band in gas-phase, which start to decrease to 130 cm−1 with increase in the ε.

#### **3.2 Solvent dependence of the H4TPP**

The UV–vis absorption spectrum of the diprotonated TPP (H4TPP) exhibited a Soret band (B-band) at 22272 cm−1 (449 nm) in *acidic* chloroform solutions [56], 22831 cm−1 (438 nm) in acidic dichloromethane solution [57], 23419 cm−1 (427 nm) in acidified THF solution [58], and 22422 cm−1 (446 nm) *and* 22272 cm−1 (*449* nm) in acidic dichloromethane solution containing chloride *anion* (Cl− ) and bromide anion (Br− ), respectively [59]. The Q(0,0)-band was observed at 14837 cm−1 (674 nm) in acidic chloroform solutions [56], 15337 cm−1 (652 nm) in acidic

*Density Functional Theory Study of the Solvent Effects on Electronic Transition Energies… DOI: http://dx.doi.org/10.5772/intechopen.99613*

dichloromethane solution [57], 15432 cm−1 (648 nm) in acidic (H2SO4) dichloromethane solution, and 15129 cm−1 (661 nm) *in* acidic (H2SO4) dichloromethane solution containing chloride *anion* (Cl− ) [59]*.* These experimental results reveal that the solvent's polarity has significantly effects on the absorption spectrum of diprotonated TPP (H4TPP). The calculated solvent effect on the absorption spectra of the H4TPP in thirty nine different solutions can summarized as follows.

**Singlet H4TPP:** On contrary to red-shifts of the bands in the absorption spectrum TPP, the solvent leads to substantial blue-shifts of the absorption bands in the protonated TPP (H4TPP) spectrum as seen in **Figure 3(A** and **B)**. For instance, the calculated Q (14761 cm−1/ 677.5 nm), B (20583 cm−1/485.8 nm), L1 (21803 cm−1/458.7 nm), L2 (24095 cm−1/415.0 nm) and M (28465 cm−1/351.3 nm) bands in gas phase spectrum are progressively blue shifted to 15352, 22981, 25069, 25731, and 29355 cm−1 (or 651.4, 435.2, 404.4, 398.9 and 388.6 nm), respectively, as function of solvent dielectric constant (ε) from 1.00 to 20.493. With further increase in ε, these electronic bands remain almost constant within a few ten of wavenumbers fluctuation. These calculated results are consistent with the experimentally observed dependence of the absorption spectrum of H4TPP on molecular environments as discussed above.

**Triplet H4TPP:** While **Figure 4(A)** provides the calculated electronic spectra of the triplet H4TPP in the solvents used in this work, **Figure 4B** provides the shifts in the peak positions as function of the solvent dielectric constant relative to their corresponding positions in the gas phase spectrum. The results from calculations show that the solvent gives rise to change in dipole allowed triplet-triplet vertical electronic transition energies in the H4TPP spectrum as well energy level of the lowest triplet state (T1) as a function of solvent dielectric constant only in the region of solvent dielectric constant from ε = 1 to 28.493 and, with further increase of solvent dielectric constant, remain unchanged within a few wavenumber variations, see **Figure 4A** and **B**. Therefore, we only provide the maximum shifts when molecular environment changes from the gas phase to acetone (ε = 28.493). It is worthy to point that the shift in the energy level of the lowest triplet state (T1) was estimated from the equation: ΔE(T1,ε) = E(T1,ε)-E(S0,ε).

The predicted T1 lowest triplet state gradually blue shifts from 8232 cm−1 (1215 nm) in gas phase to 8767 cm−1 (1141 nm) in acetone solvent medium. The T4

#### **Figure 3.**

*(A) The calculated solvent-dependence of the singlet-singlet electronic absorption spectrum of the H4TPP in the thirty-nine different environments, where the dielectric constant of the molecular environment increases from bottom (*ε *= 1.00) to top (*ε *= 181.560); (B): The red-shifts in the absorption band positions as function of dielectric constant of the solvent (*ε*), reference to their corresponding values in gas-phase spectrum.*

#### **Figure 4.**

*(A) The calculated solvent-dependence of the triplet-triplet electronic absorption spectrum of the H4TPP in the thirty-nine different environments, where the dielectric constant of the molecular environment increases from bottom (*ε *= 1.00) to top (*ε *= 181.560); (B): The shift in the energy level of the Tn state reference to their corresponding value in gas-phase spectrum as function of dielectric constant of the solvent (*ε*). The shift in the energy level of the T1 state is obtained using the equation:* Δ*E(T1,*ε*) = E(T1,*ε*)-E(S0,*ε*).*

(at 11900 cm−1/840.3 nm), T5 (13093 cm−1/763.8 nm), T6 (13955 cm−1/716.6 nm), T7 (13291 cm−1/752.4 nm), and T12 (16236 cm−1/615.9 nm) in the gas phase spectrum are 500, 1344, 1083, 2176, and 631 cm−1 blue shifted in spectrum of H4TPP in acetone, respectively. However, the T14 (19024 cm−1/525.7 nm) and T18 (21607 cm−1/462.8 nm) are 210 and 890 cm−1 red shifted in acetone as solvent, respectively, see **Figure 4A** and **B**.

The SCF corrected triplet states showed there are four ISC pathway below 30000 cm−1, which also are solvent dependent. The solvent dependence of the energy gap between the singlet and triplet excited states, ΔE(T-S; ε) = E(triplet; ε)-E(singlet; ε), decreases with increase of solvent dielectric constant up to acetone and remain almost constant with further increase of ε. For instance, when molecular environment changes from gas-phase to acetone medium, the computed energy gap (ΔE(T-S; ε)) between the closest singlet and triplet state changes from −2602 to −2458 cm−1 (T2-Q ), from 3269 to 2138 cm−1 (T3-Q ), from 743 to 208 cm−1 (T5-B), from 348 to 65 cm−1 (T11-L1), from 373 to 105 cm−1 (T12-L2), from 1076 to 5 cm−1 (T17-M) and from 1375 to 151 cm−1 (T18-M).

#### **3.3 Solvent dependence of TSPP**

Akins *et al.* [60] and Zhang *et al*. [61] also have measured the UV–vis spectra of the free-base TSPP and the H4TSPP (diprotonated- or dianionic-TSPP). The author reported that the absorption spectrum of the TSPP exhibited Q(0-0)-bands at about 517 (± 2) and 640 (± 3) nm and the B-band at ~412 nm, the H4TSPP spectrum revealed a weak broad Q(0-0)-band at 645 nm and an intense B-band at 432 nm. Furthermore, the UV–vis spectra of the singlet TSPP and H4TSPP in the region of 420-460 nm indicated that the maximum peak position of the B-band in the ethanol, methanol, and DMSO solvents is red shifted with respect to water [62].

The excited-state dynamics of the TSPP has been experimentally studied by several research groups. The lowest triplet state (T1) of the TSPP has been observed at 862 nm [63] and the energy gap between the Q1 band and the T1 state in the TSPP, ΔE(T1-Q1), is measured to be about 4000 cm−1 (48 kJ mol−1) [64]. Moreover, the measured triplet– triplet absorption spectrum of the TSPP (at pH = 7) exhibited a strong peak between 440 and 450 nm with a three weak transitions: at 524 ± 2 nm, a broad peak between

*Density Functional Theory Study of the Solvent Effects on Electronic Transition Energies… DOI: http://dx.doi.org/10.5772/intechopen.99613*

ca. 550-575 nm and third one at 624 nm [65]. For the H4TSPP (at pH = 3), their triplettriplet absorption spectrum in the range of 450-700 nm displayed two relatively strong and one weak peaks. Their estimated peak positions: at ~500 ± 2 nm with a shoulder (at about 530 nm) and 650 ± 5 nm; a weak one at about 596 ± 2 nm. Jirsa and *et al*. also observed a strong triplet band at 444 nm in the TSPP absorption spectrum [66].

Our calculated dipole allowed singlet-singlet and triplet-triplet electronic transition energies of the TSPP and H4TSPP are in good agreement with these experimentally observed absorption spectra discussed above. The results from calculations show that the spectral position of the calculated absorption bands gradually change as a function of solvent dielectric constant only in the region of ε = 1 to about 20.493 (acetone) and remain unchanged with further increase of ε. Thus, we only discuss the shifts in the band position when molecular environment changes from gas phase to acetone medium and the results may be summarized as follows.

**Singlet TSPP:** The solvent-dependence of dipole allowed singlet-singlet electronic transition energies of TSPP is given in **Figure 5A**. **Figure 5B** shows the shifts in band positions caused by solvent, which is similar to the shifts in the TPP absorption spectra. As seen in **Figure 5A** and **B**, the bands at 17064 cm−1 (Q1, 586.0 nm) and 18178 cm−1 (Q2, 550.1 nm) in the gas phase spectrum of singlet TSPP are 576 and 541 cm−1 blue-shifted to 17365 cm−1 (575.9 nm) and 18467 cm−1 (541.5 nm), respectively; however, the Soret-bands B1 at 24692 cm−1 (405.0 nm) and B2 at 25060 cm−1 (399.0 nm) in gas phase spectrum are substantially shifted as function of increasing ε up to about 20.493, such as are first 958 and 1112 cm−1 red shifted to 23734 cm−1 (421.3 nm) and 23948 cm−1 (417.6 nm) with increase of solvent dielectric constant ε from 1.0 to 5.32, and which are then turned to increase up to 24429 cm−1 (409.3 nm) and 24758 cm−1 (403.9 nm) with increase of ε from 5.32 to about 20.493. With further increasing value of ε, they remain constant within ±120 cm−1 fluctuation. The bands at 26319 cm−1 (labeled as L1 at 380.0 nm) in the gas phase spectrum is shifted to 28117 cm−1 (355.7 nm) in the same region.

**Triplet TSPP:** The solvent-dependence of the triplet-triplet vertical electronic transition energies of the TSPP is similar to these in the triplet-TPP spectrum when molecular environment changes from gas phase to solvent phase. For instance, the SCFcorrected the lowest triplet state at 10922 cm−1 (915.6 nm) exhibits a exponentially blue shift up to around 11426 cm−1 (875.2 nm) as function of the ε (up to 20.493), which then

#### **Figure 5.**

*(A) The calculated solvent-dependence of the singlet-singlet electronic absorption spectrum of the TSPP in the thirty-nine different environments, where the dielectric constant of the molecular environment increases from bottom (*ε *= 1.00) to top (*ε *= 181.560); (B): The red-shifts in the absorption band positions as function of dielectric constant of the solvent (*ε*), reference to their corresponding values in gas-phase spectrum.*

remains almost constant within 20 cm−1 with the further increase in ε. This predicted value of the T1 (lowest triplet state) in the solvent with its dielectric constant value ε ≥ 20.493 is consistent with its experimental value of 862 nm as mentioned above.

As seen in **Figure 6A** and **B**, the calculated dependence of the dipole triplettriplet vertical dipole allowed electronic transitions (T1 → Tn) energies also exhibits a exponentially red/blue-shifts as function of the ε. The triplet absorption spectrum displays the maximum shifts in acetone as solvent. For example, while the T7 at 14980 cm−1 (667.5 nm), T8 at 15282 cm−1 (654.4 nm) and T17 at 18757 cm−1 (533.1 nm) in the gas phase spectrum of the TSPP are respectively 2415, 2177 and 902 cm−1 blue-shifted (to 17295 cm−1 (574.9 nm), 17459 cm−1 (572.8 nm) and 19659 cm−1 (508.7 nm)) in acetone medium, the T24 at 22000 cm−1 (454.5 nm) in gas phase is 1036 cm−1 red-shifted to 20964 cm−1 (477.0 nm).

In the same region, T4, T5, T9 and T12 states displayed a relatively weak solvent dependence such as while the triplet states T4 (13248 cm−1/754.8 nm) and T12 (18236 cm−1/548.4 nm) display a maximum blue-shift of about 500 cm−1; the T5 (14022 cm−1/713.2 nm) and T9 (18230 cm−1/548.6 nm) triplet states exhibit about 400 cm−1 red-shift (**Figure 6B**).

For a possible inter system crossing (ISC) process, we also examined the solvent effect on the energy*-*gap between the closest singlet and the triplet states, ΔE(S-T, ISC) = E(T) - E(S). The singlet states Q2, B2 and L2 singlet states are almost overlapping with the T3 (triplet-triplet forbidden state), T4 and T8 triplet states, respectively. For instance, with changes solve ε = 1 to 20.493, ΔE(S-T, ISC) the energy-gap changes from: 234 to −40 cm−1 between the Q2 and T3 state; −2108 to −1829 cm−1 (Q1 and T2); −3322 to −2931 cm−1 (Q2 and T2); 234 to −40 cm−1 (Q2 and T3); −522 to 510 cm−1 (B1 and T4); −890 to 181 cm−1 (B2 and T4); −115 to 767 cm−1 (L1 and T8); and − 576 to 87 cm−1 (L2 and T8) with going from ε = 1 to 20.493. With the further increase in ε, they remain nearly unchanged within a few ten wavenumber variations.


*2.1.2 The rivals of school climate*

School climate can be disrupted by a range of external factors, such as certain natural phenomena (e.g. severe weather conditions) or social events (conflict, transition, loss, etc.) or by internal factors, such as the educators' and the staff's behavior, the number of students, the composition of groups, third parties entering the classroom, an accident in the classroom, and so on. In cases when the disruption is threatening to participants, we speak of a state of crisis. According to Freiberg, "a healthy school climate contributes to effective teaching and learning. These instruments for assessing climate can help schools make informed and meaningful changes for the better" ([21], p. 22). To manage states of crisis in schools, it is necessary to take measures, including school readiness, the cognitive and emotional competence of educators in matters of mental health, information on the students' family background and health, good cooperation with educational institutions, parents, school administrators and educators, and clearly defined and predetermined rules of action. Hoy et al. note that "A healthy school climate is imbued with positive student, teacher, and administrator interrelationships. Teachers like their colleagues, their school, their job, and their students are driven by a quest for academic excellence" (2002:39) [22]. According to Marshall [23], school climate is influenced by the following factors:

• The number and quality of interactions between adults and students;

*Beyond Teaching: School Climate and Communication in the Educational Context DOI: http://dx.doi.org/10.5772/intechopen.93575*

School atmosphere can have an impact on many areas of the school experience. Positive school climate has been associated with fewer emotional and behavioral problems [24]. Commitment to compliance with school operational rules and positive feedback by educators are two aspects of the pedagogical climate that affect the school experience and students' self-esteem [25]. In addition, a special research project into school climate in high-risk urban settings has shown that a positive and supportive school climate can affect students' academic performance to a great extent [26]. According to another research project, positive interpersonal relationships and an increase in learning opportunities for students in all demographic settings can increase levels of achievement and decrease dangerous behavior [27].

Regarding the roles of the teaching and administrative staff, Taylor and Tashakkori [28] found that the existence of a positive climate in school is connected to an increased sense of job satisfaction for school staff. Finally, the transition from one educational level to the next is also influenced by school climate. Entering a new school can cause stress in teachers and students, and this can have a negative impact on the teaching and learning process. Research has found that a positive and supportive school climate is important for a smooth transition to a new school [21]. Establishing a positive climate in a school unit is a collective, coordinated, and, to a certain degree, disciplined endeavor by the whole staff. When teachers and students feel that they are in an environment that is truly and actually interested in them, they view their everyday teaching and learning experience as a positive process ([29], p. xi). These are schools where staff exhibit a passionate professionalism and enjoy extensible opportunities for collegial dialog, problem solving, and community building and where the culture encourages student involvement in community service and teacher commitment to continual instructional development ([15], p. 29).

#### *2.1.3 Evaluation of school climate*

Evaluating school climate is one of the best ways to ensure its positive characteristics. An environment of cooperation and learning is founded on the social and emotional environment of the school, which is reflected in school climate [9, 30]. The evaluation process is aimed at assessing the level of school climate and designing its further improvement so that schools with a positive school culture can be created. Although traditionally the assessment of student performance has used reading, mathematics, and scientific knowledge as its criteria, an increasing number of education agencies are realizing that these indicators cannot convey educational outcomes in their totality. Data from the assessment of school climate are now used as a complementary form of evaluation. Important information is derived from the reviews of students in their final year. As Freiberg stresses, "the feedback process allows students to be citizens rather than tourists in their school, as they realize that they have an opportunity to participate in shaping the education process" ([21], p. 26).

The school community determines policies that promote the holistic development of all participants in the school community—the social, emotional, moral, political, and intellectual. Also, it promotes an integrated system for overcoming hindrances during teaching and learning. We could say that the school community creates an environment in which all members feel safe and creative. School climate and relationships within the school are one of the main areas of evaluation in the assessment programs for schools. Specifically, during the evaluation process, attention is paid to the following criteria of quality:

*Relationships among educators*: Quality of communication, creative collaboration and collective action, regular meetings, and cooperation with emphasis placed on pedagogical and teaching issues.

*Relationships between educators and students and among students themselves*: The pedagogical teacher-student relationship, development of initiatives for creative teacher-student cooperation, student conduct that complies with school rules, and student participation in the formulation of regulatory practices pertaining to school life.

*Relationships between school and parents*: Effective mechanisms for regular and two-way communication between the school and parents, quality of the information exchanged with parents, development of initiatives for creative cooperation with the Parents' Association.

*Relationships between the school and agencies*: Constructive communication and collaboration with education authorities and agencies, the local community and the broader society, frequency, content, and quality of communication [31].

The process of evaluating and improving school climate is a demanding one. It is understood as a circular process consisting of five stages, including preparation and planning, assessment-evaluation of strengths, weaknesses, and needs, understanding evaluation outcomes, designing and application of the action plan, and reassessing what has been achieved and developing the next stage for improving school climate. The evaluation of indicators is based on data collected through the use of qualitative and quantitative methods and observation and recording tools [32]. The quality of education is, to a great extent, a function of school climate quality, which can be improved substantially, especially when it is understood and evaluated internally by the individuals actually involved in the education process. Internal evaluation requires additional competences on the educator's part, but experience has shown that educators avoid recording data of their pedagogical action. The collection of data with the use of various methods identifies the educator as an education researcher, a quality inherent in pedagogical action. A combination of methods and techniques for observation and recording is the most effective way to cross-check and interpret data, and to define goals for each of the stages of evaluation [33].

School climate is expressed by tangible means, it is greatly influenced by leadership, and it responds to change rapidly. It becomes evident through collectivity, communication, decision-making, trust, expectations, recognition, support, and experimentation. School climate should reflect directly the school's mission statement through its focus and actions. External factors, such as increased funding and provision of resources and staff can play a key role in shaping positive school climate. We are aware, however, that when planning and interventions are carried out by those involved in the internal environment of the school, they tend to be more viable. Could internal school communication be efficient in this respect? This question is analyzed in the following section.

#### **2.2 Communication in educational context**

#### *2.2.1 Concept and definition*

Communication is the main parameter in the creation and development of civilization. For ancient Greeks and Romans, it was an area of great importance. *Beyond Teaching: School Climate and Communication in the Educational Context DOI: http://dx.doi.org/10.5772/intechopen.93575*

The Athenian society called for greater competence in oral speech. When in court, citizens could not hire advocates but, rather, they had to defend themselves publicly. Those who stood for public office had to learn how to voice their ideas clearly and convincingly. In an attempt to understand the variables affecting persuasion, modern scholars have tried to transfer the classical persuasion practice into modern reality.

A multitude of definitions can be found in the literature with regard to communication. It has been defined as the delivery, reception, processing, and interpretation of information. This information can be transmitted orally, in writing, and in an active, passive, formal, informal, conscious, or unconscious manner ([34], p. 290). Robbins, Coulter and DeCenzo note that communication is the transfer of understanding and meaning ([35], p. 446). According to Schermerhorn [36], communication is an interpersonal process of sending and receiving symbols with attached messages. Communication is an interpersonal, that is, a social process, which can only be considered complete when some kind of understanding has been reached. It never is a simple case of a stimulus and a response in the way that these terms are used in psychology. Communication is the mechanism by means of which human relationships exist and develop. Irrespective of its conceptual definition, it must involve not only the transfer of meaning but also an understanding of it. Only when the sender's message is fully understood by its recipient(s) can communication be considered effective ([34], p. 294; [36], p. 491).

Communication is a social activity, a social phenomenon that is present both at the interpersonal level and at the organization level. Communication is about transmitting and receiving information and messages between individuals and between groups through a system of symbols. Educators, just like doctors, social workers, psychologists, vocational guidance and business counselors, etc., are what is called "interpersonal professionals", meaning that a great part of their work is dedicated to face-to-face interactions with other people. Such professionals must possess certain skills:

It is a fact that the ways used to communicate today have increased significantly compared to the past [38, 39]. Although educators have several new possibilities and media at their disposal that enable them to send their message to multiple audiences, they still seem to be lacking in key communication skills. It is also true that educators are not concerned about the way and the outcomes of their communication with students on the micro-scale of the classroom. However, experience has shown that this is not the case when they need to collaborate and communicate with other groups, such as staff associations, parents' associations, and education agencies. On such occasions, the necessary communication skills are situated on the macro-level of the social and political sphere, where argumentation and persuasion require more complex knowledge and skills [40].

Conversation analysis in the school context aims to highlight the kinds of conversation that are most effective in students' understanding of the material taught. Most research focuses on teacher-student dialogs [41–43], while studies into student-to-student talk within the education process are rather limited in number. The orality movement has helped to emphasize the significance of oral discourse

in the school context. Regarding the systematic research of talk, two models of communication have been proposed. The *Transmission Model of Communication* views oral discourse as a medium for the transmission of information between a sender and a recipient. Although this model is held in high regard in educational practice, it fails to penetrate the complexity of oral discourse ([44], p. 132). The second model, the *Dialogic Model* [45] draws on Piaget and Vygotsky and their constructive process of discourse. According to the *Dialogic Model*, understanding between interlocutors is constructed through dialog and is shaped by the social and cultural context. Hence, talk is a complete system of cooperative understanding. The dialogic model is also connected to Volosinov and Bakhtin, according to whom utterances and responses constitute a chain of interlinked verbal events [44].

#### *2.2.2 Listening culture*

*Listening* is a complex parameter of communication rather than a simple and natural hearing process. According to the Speech Communication Association, listening is the process of receiving and assimilating ideas and information from spoken messages. Effective listening involves both the literal and the critical understanding of ideas and information transmitted through oral speech ([46], p. 282). Listening is an active process that the individual chooses to occur. Of the events that take place in his environment, the individual selects the ones to which he will direct his attention, which he processes and uses, and which he may even retain and combine with other bits of information that he has previously chosen to save in his memory. The skills of active listening can be cultivated through practice and knowledge acquisition [47]. However, communication can encounter difficulties deriving from a failure to listen. Such hindrances include listeners who do not actually listen but pretend to do so, *selective listeners*, who employ a kind of partial listening whereby they deliberately direct their attention to certain parts of the speaker's talk, and, finally, *egocentric listeners*, who regard themselves as the center of each and every transaction or activity [46]. For a listening culture to be developed, emotional intelligence and empathy on the part of those involved are essential. Listening culture is a determining factor in promoting collaboration among educators and in shaping positive school climate.

According to contemporary educational research, communication is one of the main factors in the development of a sustainable system for improving school climate ([29, 48], p. xv). Within a school unit the whole of the educational workforce communicates with one another, with colleagues from other school units, with the community of parents, but also with various agencies from outside the school [49]. The communication process occurs on a daily basis with all educators within school orgnanizations. For cooperational relationships to be developed in the school, effective communication among members of the school community is considered essential ([35], pp. 428–36). Sergiovanni notes that "School climate and relationships are obviously affected by the organization and communication in the school; school climate lies at the center" ([50], pp. 100–101).

#### *2.2.3 Communication and leadership*

School principals' communication skills can determine, to a large extent, school efficacy and the achievement of goals. Research has shown that school principals devote a great amount of time to communicating with students, other educators, parents, education authorities, and with other individuals relevant to the school environment ([51], p. 53). According to certain findings, their communication is not rigidly planned, but, rather, spontaneous and relaxed, while they do not seem to make a systematic effort to receive or provide feedback or evaluate the

#### *Beyond Teaching: School Climate and Communication in the Educational Context DOI: http://dx.doi.org/10.5772/intechopen.93575*

effectiveness of communication. In addition, the communication roles assumed by school principals have increased, mainly because of the possibilities provided by new technologies. Gordon and Alston [10], 97–99) talk about four communication roles of principals: a) communication agent, b) message recipient, c) supervisor, and d) communication seeker.

In a critical analysis of these roles, we could suggest that the roles of the agent and recipient are somewhat inherent in the principal's responsibilities, while the roles of supervisor and seeker require the development of communication skills and practices by the principals themselves. The role of a communication agent requires, first and foremost, that the principal understands the main objective of the message they wish to transfer [52]. When they understand the purpose of the message, they will be able to determine precisely both its content (message encoding) and the appropriate means of transmission (communication channel) ([36], pp. 491–493). At the same time, they must be aware of potential obstacles that may arise in the process of decoding by the person or persons that the message addresses (recipients). Such obstacles can be lack of interest on the recipients' part, their poor cognitive background, prejudice, a problematic situation, etc. An important factor in this process is the existence or nonexistence of mutual trust between the agent and the recipient. Trust, i.e., confidence in the integrity, personality, and competences of a manager, constitutes a key parameter of communicative efficacy, as it is through this trust that the principal can convince recipients of the legitimacy of the objectives involved in the message ([35], p. 413). The role of recipient requires that principals be active listeners who try to decodify the sender's messages without making judgments or resorting to spontaneous interpretations. Instead, they should engage in close observation of nonverbal clues, avoiding distractions and, above all, strengthening empathy for the sender. But how capable are school principals of understanding the emotions of others, including educators? With a certain degree of emotional intelligence, school principals can "read" other people's feelings by focusing communication on actual behaviors, such as verbal, nonverbal, and paralinguistic clues. Communication is of great importance when it comes to understanding and interpreting the feelings of others, that is, their emotional intelligence. Donaldson [53] researched his own high school principalship by surveying staff members regarding communication. He analyzed both direct and indirect forms of communication finding a discrepancy between how he saw himself and how his staff members saw him.

Teachers are in a state of ongoing interaction and communication. The quality of this interaction is mainly dependent on the form of communication they use. An authoritarian attitude and administration turn workers into passive and submissive individuals and can ruin any possibility for meaningful communication and interaction. By contrast, a democratic attitude can contribute to the creation of a better emotional climate of cooperation, optimism, sincerity and responsibility and provides better possibilities for working efficiently and developing the personalities of those involved. A democratic principal can help create a positive school climate and, by doing so, a climate that is also productive. A principal who is demanding, pressing, and authoritarian cannot foster the improvement of interpersonal relationships. By contrast, a friendly, democratic principal can contribute substantially to the development of good relationships among the staff, which is a necessary condition for the progress of the whole organization. "School leaders—principals, teachers, and parents—are the key to eliminating toxic culture and building positive culture" ([15], p. 28).

To conclude, it can be argued that school principals should not restrict their communication roles to sending and receiving messages. Supervising and seeking communication within, from and to the school unit are quality features for establishing an appropriate process of communication than can make a difference in

the lives of all stakeholders—educators, students, and parents. These roles call for a principal who is constantly active and has a profound insight, a principal whose vision will be the enhancement of communication at all levels so that a climate of trust can be created and communication can be promoted.

#### **2.3 Meta-analysis approach of the literature**

The problem set forth in this study is based upon the changes in educational context as caused by current social, financial, and technological factors, and their impact on school climate. This analysis explores the variables of school climate and communication in order to find the extent to which their relationship can work in favor of an open, safe, and creative educational organization where a positive school climate exists, and to which teachers and students will wish to belong.

#### *2.3.1 Literature identification*

The conceptual framework of this study is based on research related to organizational culture and educational communication. The material analyzed consists of contemporary articles and books, which highlight the importance of positive school climate in achieving school objectives, and interpersonal communication as a determining factor in terms of the research questions posed.

#### *2.3.2 Articles selection*

The examination of literature developed on a general-to-specific basis. By constructing the specific research question, we narrowed the focus of the research. We decided on the specific preliminary research question and identified key concepts and preliminary search terms. We selected appropriate databases in library catalogs and on the World Wide Web open access journals.

#### *2.3.3 Method of literature analysis*

This study is a critical meta-analysis of literature on the research hypothesis, that communication is a key factor in promoting positive school climate. Metaanalysis is a recent trend in research. It refers to analyzing published studies to examine trends in the literature or in the results of research studies, such as the impact of a certain independent variable on another [54, 55]. By combining results found in scholarly journals and chapters, researchers can tell how much of an effect a particular variable has had over time.

The availability of electronic databases containing the results of published studies was a substantial benefit for the researcher conducting this meta-analysis. Databases such as https://eric.ed.gov/, www.ascd.org, https://www.hepg.org/, http://education.gsu.edu/, and databases of libraries were used. Sixty articles and books on the subject were selected that cover the key aspects of the topic and the new directions. A thorough study and analysis of their content was performed.

## **3. Results and discussion**

These results are presented and discussed under subthemes, which addressed the questions posed for this study. Thus, the subthemes: "The concept and the importance of school climate", "The Rivals of school climate", and "Evaluation of school climate" emerged for, for the theme "School Climate" and "*Concept and*

*Definition",* "Listening Culture", and "Communication and Leadership were formed for the theme "Communication in Educational Context". A specific aspect of the problem is clarified in discussing each section of the literature review results.


*3.3.3 Coatzacoalcos bridge: Mexico infrastructure*

The cable-stayed bridge located in Veracruz, Mexico consists of two main reinforced concrete towers that support the main deck with cable tensors and the slab stiffened by two reinforced concrete girders. The structure has a total length of 3838 feet (1170 m) and a span length of 944 feet (288 m). **Figure 10** shows an overview of the structure.

> The bridge consists of 15 supports, 14 sections and the main structure. The towers and secondary columns are made of reinforced concrete; the main girder is shaped like a drawer with reinforced concrete and the cable tensors supporting the main deck are made of structural steel. It was inaugurated in 1984 and considered

This cable-stayed bridge is located in the city of Jerusalem and has a total span of

The main feature of this bridge belongs to the architecture and geometry. It was designed by Santiago Calatrava, a world-renowned architect and engineer, and the user can recognize the structure as an unconventional bridge. As shown in **Figure 11**, we can see the special geometry of the main tower and each of the cable tensors, showing a harp shape. In addition, the main deck has a curved form.

The structure was inaugurated in 2008 marking a symbol in the city of Jerusalem. Due to the great height of the main tower and its harp-shaped geometry, the

Due the large number of variables on the conceptual design of a structure, there is no special formula for determining the best option of a bridge. Many variables come into play, from the experience of the engineers and architects, to the specific needs of the place, such as topography, soil characteristics and materials availability. There are several models to describe the general process of design, built, opera-

tion and maintenance of a bridge in a general way. One of the most compact

The process for any bridge design consists of input data, regulations, design

flowcharts was proposed by Addis [13], shown in **Figure 12**.

1181 feet (360 m). The bridge aims to help the city light trail system and the structure consists of a main tower connecting the structural steel slab using 70 steel

one of the largest structures in Mexico.

*Jerusalem cable-stayed bridge [12].*

**Figure 11.**

cables and reinforced concrete supports.

*3.3.4 Jerusalem bridge: architecture and modernity*

*Bridges: Structures and Materials, Ancient and Modern DOI: http://dx.doi.org/10.5772/intechopen.90718*

bridge can be appreciated from any place of the city.

**4. Bridges construction and materials**

process and results, explained as follows:

**105**

**Figure 9.** *Tacoma narrows suspension bridge, under aerodynamic vibrations [10].*

**Figure 10.** *Coatzacoalcos II cable-stayed bridge overview [11].*

*Bridges: Structures and Materials, Ancient and Modern DOI: http://dx.doi.org/10.5772/intechopen.90718*

**Figure 11.** *Jerusalem cable-stayed bridge [12].*

a. Very high slenderness ratio of the bridge.

*Infrastructure Management and Construction*

structures, including bridges of very large spans.

*3.3.3 Coatzacoalcos bridge: Mexico infrastructure*

*Tacoma narrows suspension bridge, under aerodynamic vibrations [10].*

overview of the structure.

**Figure 9.**

**Figure 10.**

**104**

*Coatzacoalcos II cable-stayed bridge overview [11].*

b. Use of girders instead of truss as deck stiffener.

c. Obstruction of air flow due the girder itself, causing whirlwind.

After this event, studies on aerodynamics and aero-elasticity topics in the structures increased significantly, developing procedures to simulate these events on

The cable-stayed bridge located in Veracruz, Mexico consists of two main reinforced concrete towers that support the main deck with cable tensors and the slab stiffened by two reinforced concrete girders. The structure has a total length of 3838 feet (1170 m) and a span length of 944 feet (288 m). **Figure 10** shows an

> The bridge consists of 15 supports, 14 sections and the main structure. The towers and secondary columns are made of reinforced concrete; the main girder is shaped like a drawer with reinforced concrete and the cable tensors supporting the main deck are made of structural steel. It was inaugurated in 1984 and considered one of the largest structures in Mexico.

#### *3.3.4 Jerusalem bridge: architecture and modernity*

This cable-stayed bridge is located in the city of Jerusalem and has a total span of 1181 feet (360 m). The bridge aims to help the city light trail system and the structure consists of a main tower connecting the structural steel slab using 70 steel cables and reinforced concrete supports.

The main feature of this bridge belongs to the architecture and geometry. It was designed by Santiago Calatrava, a world-renowned architect and engineer, and the user can recognize the structure as an unconventional bridge. As shown in **Figure 11**, we can see the special geometry of the main tower and each of the cable tensors, showing a harp shape. In addition, the main deck has a curved form.

The structure was inaugurated in 2008 marking a symbol in the city of Jerusalem. Due to the great height of the main tower and its harp-shaped geometry, the bridge can be appreciated from any place of the city.


Dinesh Kumar Sharma

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/66486

#### **Abstract**

Meniere's disease is a progressive disorder characterized by recurrent episodes of spontaneous vertigo, sensorineural hearing loss and tinnitus, often with a feeling of fullness in the ear. The exact ethology is not known. In 1972, a diagnostic criterion for Meniere's disease was proposed by American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS), and till date, it has been revised twice in the years 1985 and 1995. The principal audiological investigation is pure tone audiometry combined with a glycerol test. Speech audiometry and otoacoustic emissions also play a limited role. The value of electrocochleography is limited.

**Keywords:** pure tone audiometry, glycerol test, speech audiometry, OAE, electrocochleography

## **1. Introduction**

Meniere's disease named after an Italian scientist, Prosper Meniere, is a progressive disorder characterized by recurrent episodes of spontaneous vertigo, sensorineural hearing loss and tinnitus, often with a feeling of fullness in the ear [1]. The characteristic of the disease is that it is an unpredictable, fluctuating illness with noteworthy hidden disability [2].

The precise cause of Meniere's disease is still being investigated. It is believed to be associated with endolymphatic hydrops, that is, raised endolymph pressure in the membranous labyrinth of the inner ear, which gets dilated like a balloon when pressure increases and drainage is blocked. This results in swelling of the endolymphatic sac and other tissues in the vestibular system (responsible for the body's sense of balance), creating an acute vestibular imbalance, resulting in vertigo and fluctuating hearing loss [3].

Another suggested etiology is the autoimmune nature of the disease. The idea of autoimmunity was brought forward when improvement in bilateral progressive sensorineural hearing

loss was recorded following immunosuppressive therapy. The studies of the human endolymphatic sac have also suggested that it is the primary immunocompetent structure in the inner ear, which is capable of processing antigen, synthesizing antibodies and raising a cellular immune response [4].

No single test that makes the diagnosis of Meniere's disease with conformity has been established. Complete history, including a detailed description of the pattern of disease presentation supported by quantitative testing, helps in arriving at a diagnosis [5].

A number of international interdisciplinary organizations in a consensus paper have drawn diagnostic criteria for Meniere's disease. The paper suggests two categories of the Meniere's disease, definite and probable. The definition of definite variety incorporates a clinical criteria and observation of episodes of vertigo associated with audiometric findings of sensorineural hearing loss involving low and middle frequencies and triad of symptoms that include fluctuant hearing loss, tinnitus and/or fullness of the involved ear. The criteria limit the duration of vertigo from 20 min to 12 h. The definition of probable variety of Meniere's disease encompasses vertigo or dizziness and extends to episodic ear-related symptoms, which may occur for a variable period time between 20 min and 24 h [2].

The natural history of Meniere's disease is inconstant but usually progressive. The classical triad of tinnitus or aural fullness with episodic vertigo and hearing impairment is often not seen at the beginning of the disease. The disease starts as a single symptom entity, and only cochlear symptoms occur at the first stage. The period between the primary symptoms and the manifestation of other symptoms varies from months to several years with an estimated average of 6–18 months. After this period of variable duration, the complete triad of symptoms will appear [6].

Episodic attacks of vertigo (so-called Meniere's attack) are the most troublesome of the symptoms to the patient, and it is usually the symptom that causes the patient to seek medical treatment. The vertigo patient perceives either that the world is spinning around them or that they themselves are spinning. Typically, it occurs in the form of a series of attacks over a period of weeks or months, interspersed by periods of remission of variable duration [7].

When the patient experiences a feeling of rotation, the sign is nystagmus, which has been described as a condition of involuntary movements of eyeball. This is accompanied by other symptoms such as giddiness and sweating [8].

On most occasions, patients experience a heaviness or fullness of the involved ear, which is accompanied by impairment of hearing and ringing sensation. Often the beginning of symptoms is precipitous, which reaches its zenith within a span of minutes to hours. The entire episode persists for an hour so before it wanes. The patient may experience unsteadiness for a couple of hours or days after the attack subsides. In between episodes of the disease, subjects may suffer from positional vertigo [9].

Vertigo is the most disabling one among the cardinal symptoms of the disease. It adversely affects almost every aspect of life disturbing the normal lifestyle of the patient. The vertigo is made worse especially when movement is involved. Patient's ability to lead a normal way life is hampered by risks of fall. The chances of such events are made worse by small head movements, which make the patient subjectively very "ill." Vertigo can completely undermine the individual. This leads the patients to confine themselves to bed until the symptoms improve [10].

loss was recorded following immunosuppressive therapy. The studies of the human endolymphatic sac have also suggested that it is the primary immunocompetent structure in the inner ear, which is capable of processing antigen, synthesizing antibodies and raising a cel-

No single test that makes the diagnosis of Meniere's disease with conformity has been established. Complete history, including a detailed description of the pattern of disease presenta-

A number of international interdisciplinary organizations in a consensus paper have drawn diagnostic criteria for Meniere's disease. The paper suggests two categories of the Meniere's disease, definite and probable. The definition of definite variety incorporates a clinical criteria and observation of episodes of vertigo associated with audiometric findings of sensorineural hearing loss involving low and middle frequencies and triad of symptoms that include fluctuant hearing loss, tinnitus and/or fullness of the involved ear. The criteria limit the duration of vertigo from 20 min to 12 h. The definition of probable variety of Meniere's disease encompasses vertigo or dizziness and extends to episodic ear-related symptoms, which may occur

The natural history of Meniere's disease is inconstant but usually progressive. The classical triad of tinnitus or aural fullness with episodic vertigo and hearing impairment is often not seen at the beginning of the disease. The disease starts as a single symptom entity, and only cochlear symptoms occur at the first stage. The period between the primary symptoms and the manifestation of other symptoms varies from months to several years with an estimated average of 6–18 months. After this period of variable duration, the complete triad of symp-

Episodic attacks of vertigo (so-called Meniere's attack) are the most troublesome of the symptoms to the patient, and it is usually the symptom that causes the patient to seek medical treatment. The vertigo patient perceives either that the world is spinning around them or that they themselves are spinning. Typically, it occurs in the form of a series of attacks over a period of

When the patient experiences a feeling of rotation, the sign is nystagmus, which has been described as a condition of involuntary movements of eyeball. This is accompanied by other

On most occasions, patients experience a heaviness or fullness of the involved ear, which is accompanied by impairment of hearing and ringing sensation. Often the beginning of symptoms is precipitous, which reaches its zenith within a span of minutes to hours. The entire episode persists for an hour so before it wanes. The patient may experience unsteadiness for a couple of hours or days after the attack subsides. In between episodes of the disease, subjects

Vertigo is the most disabling one among the cardinal symptoms of the disease. It adversely affects almost every aspect of life disturbing the normal lifestyle of the patient. The vertigo is made worse especially when movement is involved. Patient's ability to lead a normal way

weeks or months, interspersed by periods of remission of variable duration [7].

tion supported by quantitative testing, helps in arriving at a diagnosis [5].

for a variable period time between 20 min and 24 h [2].

symptoms such as giddiness and sweating [8].

may suffer from positional vertigo [9].

lular immune response [4].

72 Up to Date on Meniere's Disease

toms will appear [6].

Some sufferers experience "drop attacks," which are sudden, severe unexplained falls without loss of consciousness or associated vertigo. These drop attacks are due to acute utriculosaccular dysfunction and are triggered by changes in inner ear pressure affecting otolith function [11].

Another unusual pattern of clinical presentation has been described, known as Lermoyez attacks. As opposed to typical spells in which tinnitus and hearing loss precede and worsen with the onset of vertigo, in Lermoyez attacks increased tinnitus and hearing loss precede the vertiginous episode and dramatically resolve with onset of vertigo [12].

Tinnitus experienced by Meniere's patients is continual and does not abate with time, although its intensity may vary. In addition, it may be heard more as a loud roaring or buzzing sensation, rather than a whistling, and is most commonly non-pulsatile and of the lowfrequency type. The pitch tends to be related to the region of the most severe hearing loss and the magnitude of tinnitus roughly proportional to the severity of hearing loss [13].

A sensation of aural fullness that may precede a definite vertiginous spell, is considered a symptom alternative to tinnitus in the criteria of AAO-HNS (1985, 1995) and is experienced by 74.1% of the patients [14].

The hearing loss usually affects one ear, which typically loses sensitivity to low-frequency sounds and is of sensorineural type. As the hearing thresholds rise, dynamic range decreases, the sounds are typically described as "tinny" by the patient, the quality of sounds becomes poor, and loudness of loud sounds rises rapidly due to a phenomenon known as recruitment. The patients become intolerant to such loud sounds. During the early days of the disease, the hearing loss tends to return to within normal thresholds, and however, later in course of disease, hearing loss persists and even deteriorates over the course of following episodes. Even in terms of frequency involvement, the hearing loss spreads to involve all the frequencies showing a flat line on the audiogram. The sensorineural hearing loss in Meniere's disease involves low frequencies giving a flat audiometric pattern, but sometimes we get peak audiograms that are nearly normal hearing at around 2 kHz and decreased sensorineural hearing at lower and higher frequencies. This type of pattern is considered to be diagnostic of Meniere's disease and is more commonly seen in patients with disease of short duration. Over time, the hearing loss flattens and becomes less variable [15].

Patients become profoundly deaf rarely in 1–2% of severely affected patients [2].

Additional features are diplacusis that is unusual sensitivity to noises, sounds can seem tinny or distorted known as dysacusis, a difference in the perception of pitch between the ears (43.6%) and recruitment (56%) [16].


**1. Introduction**

Microscopic interferometry is a combination of an electronic speckle pattern interferometry (ESPI) system and a microscopic optical path. It has the advantages of non-contact, full-field and high precision, and is widely used in dynamic and static measurement of micro devices [1–5]. ESPI has been developed for many years and is very popular in the field of non-contact measurement. By analyzing the interferograms, we can obtain the phase information of the measured object, and then the static morphology or dynamic deformation can be measured. Researchers have designed a variety of optical measurement configurations and phase processing algorithms for different measurement targets. In 1971, Butters, J.N. and Lecndcrtz, J.A. used a camera instead of a holographic dry plate to record the interference phenomenon of speckles. This series of speckle images can be electronically processed to compare the speckle images before and after deformation [6]. Jones, R. comprehensively analyzed the conditions for obtaining the best performance of the ESPI, such as camera characteristic, laser power, interferometer type and operation mode, which provide a general theoretical basis for the system design and optimization of various interferometers [7]. In reference [8], a detailed analysis of the vibration fringes obtained by phase stepping on a time-averaged electronic speckle pattern interferometer was presented. Moore, A.J. presented two phase-stepping algorithms that can calculate phase from ESPI fringes: the subtraction method and the addition method. Corresponding interference experiments were carried out, combining a piezoelectric transducer (PZT) and pulse laser, and the function of the algorithms was demonstrated through the collected interferograms [9]. One-shot phase-shifting optical and speckle interferometry with modulation of polarization was described in reference [10]. The system has the ability to record multiple phase-shifting optical or speckle patterns at the same time, so it can afford to measure rapid changes generated from rapid varying phenomena. However, this method reduced the spatial resolution while increasing the time resolution. Reference [11] reported a simple, compact ESPI incorporating a holographic optical system for the study of outof-plane vibration. The subtraction method was used to generate the fringe pattern. The

**Citation:** Gao, C.; Gao, Z.; Niu, Y.; Wang, X.; Zhao, J.; Deng, L. An Improved Large-Field Microscopic Speckle Interferometry System for Dynamic Displacement Measurementof MEMS. *Photonics* **2021**, *8*, 271. https://doi.org/10.3390/photonics 8070271

Received: 21 June 2021 Accepted: 7 July 2021 Published: 9 July 2021

**Publisher's Note:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

**Copyright:** © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

background speckle noise was eliminated by introducing a phase shift between consecutive images, and finally the amplitude and phase image were obtained through path difference modulation. D. Malacara summarized and described common phase-detection algorithms in interferometry, such as the least square method, quadrature phase method and discrete low-pass filtering, etc. [12]. These theories are very helpful for us to obtain the phase under a variety of different measurement conditions.

With the rapid development and wider application of MEMS, there are more and more studies on the measurement of micro devices. The measurement of micro devices can be achieved by introducing the microscopic optical path into the interferometry system. Reference [13] described an optoelectronic holography microscope (OEHM) for measuring static and dynamic modes of MEMS accelerometers with submicron accuracy. After obtaining the intensity patterns obtained by the phase-stepping algorithm, the phase value was obtained by the phase-shifting algorithm. Preliminary results indicate that the MEMS accelerometer considered in this study deforms by 1.48 μm. Kumar, U.P. presented a two-wavelength micro-interferometric setup for 3-D surface profile characterization of smooth and rough micro-specimens. The method removed ambiguity associated with the single-wavelength data and also extended the phase measurement range compared to the conventional single-wavelength interferometry. A seven-phase step algorithm was used for quantitative fringe analysis. The experimental results on rough silicon membrane and smooth sample were presented [14]. Reference [15] proposed a multiple-wavelength microscopic holographic configuration. This system used sequentially recorded phaseshifted frames at three different wavelengths to evaluate the relatively large deformation fields at the effective wavelengths. The phase distribution before and after loading the object was obtained by using the eight-phase step algorithm. The design of the system along with the experimental results on small-scale rough specimens under static load was presented.

In addition to the above several configurations, according to the optical path structure and the position of the microscope, the commonly used microscopic interferometry systems can be divided into three types: Michelson type [16–19], Mirau type [20–24] and Linnik type [25–33]. For example, Wiersma, J.T. used the Michelson microscopic system and synchronous phase sensor to realize high precision and repeatable measurement of common vibration [19]; Schmit, J. proposed an improved Mirau interferometer, which can generate orthogonally polarized output beams, and can obtain better fringe contrast by introducing achromatic phase shift [21]; Somekh, M.G. realized a plasmon microscope with sub-micron resolution by using the Linnik interferometer with speckle illumination [26]; Li, X.D. of Tsinghua University measured the thermal deformation of copper microbridges with different sizes (the maximum size is 2175 μm × 1009 μm) in real time using the Linnik microscopic interferometry system, and the accuracy reached submicron level [33].

Compared with ESPI, the microscopic interferometry system can achieve high-resolution measurement of micro devices. However, at the same time, the microscopic system is limited by the field of view of microscope, and the measurement range is very small. Considering that the size of MEMS is in the micron level to the millimeter level, especially after packaging, the size of many MEMS is in the millimeter level. For micro devices in this size range, the microscopic interferometry system is no longer sufficient to achieve full-field measurement. In this paper, a large-field microscopic speckle interferometry system based on an improved Mach–Zehnder structure is proposed. Our measurement system has two main advantages: 1. under the conditions of using the same microscope objective, compared with the traditional Linnik structure, the new system expands the field of view from a circular area with a diameter of 2.4 mm to a rectangular area of 6 mm × 8 mm; 2. it can reduce the reflected light beam in the optical path, thereby reducing the reflected coherent noise.

The phase extraction algorithm used in our work is the wavelet transform (WT) method, which is described in detail in our previous article [34]. Compared with the phase shifting method that appears many times in the above references, the WT does not need to

introduce multiple steps by PZT, which saves a lot of time. Additionally, WT can directly convert the phase change signal from the spatial domain to the frequency domain to realize real-time measurement of the displacement or deformation of the measured object. We used the new system and WT to perform real-time and large-field measurement on a large area of MEMS. Detailed principles and experiments will be introduced below.


**2. State of art – Cyber attacks, event correlation and forecasting**

In this section we approach event correlation for detecting cyber-attacks, the forecasting methods used to predict cyber-attacks and Distributed Architecture for Intrusion Forecasting System (DIFS (Pontes & Guelfi, 2009), (Pontes & Zucchi, 2010).


**Author details**

Stanislaw P. Stawicki1 \*, Ricardo Izurieta2 , Michael S. Firstenberg3 and Sagar C. Galwankar4

1 Department of Research and Innovation, St. Luke's University Health Network, Bethlehem, Pennsylvania, USA

2 College of Public Health, Morsani College of Medicine, University of South Florida, Tampa, Florida, USA

3 Department of Research and Special Projects, William Novick Global Cardiac Alliance, Memphis, Tennessee, USA

4 Department of Emergency Medicine, Sarasota Memorial Hospital, Florida State University College of Medicine, Sarasota, Florida, USA

\*Address all correspondence to<EMAIL_ADDRESS>
© 2022 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.

*Introductory Chapter: Transitioning International Health Security Focus from COVID-19… DOI: http://dx.doi.org/10.5772/intechopen.107277*