**14. Thromboelastography**

Thromboelastography was first described in 1948. Viscoelastic changes during coagulation are plotted against time(42). The abbreviation 'TEG' was used for this technique. TEG® is now a trademark for one manufacturer of thromboelastograph device, an alternative manufacturer uses the trademark ROTEM®. The principles are similar, described below.


**2.1 Financial market structure and challenges in Ghana**

The financial market of Ghana is a segment of the larger economy and plays an integral role in driving economic growth, development, and stability in the country. Ghana's economy is heavily reliant on external sources of capital, such as foreign aid and external borrowing, and thus the management of these funds and the functioning of the domestic financial market are of utmost importance. A thorough understanding of the structure and challenges of the financial market in Ghana is thus necessary to maintain a healthy and sustainable economy. The financial market of Ghana is composed of traditional financial intermediaries such as banks, non-banking financial institutions, microfinance institutions, insurers, and other non-banks. These institutions are regulated by the Bank of Ghana, the central bank of Ghana, to ensure the soundness, efficiency, and stability of the system. Furthermore, the Bank of Ghana plays an active role in the regulation of the capital and money markets of Ghana, as well as overseeing the activities of the non-bank financial intermediaries [10].

Despite the presence of the Bank of Ghana's regulatory role, various challenges hinder the effective functioning of the financial market in Ghana. These challenges can be categorized broadly into three main areas: deficient financial infrastructure, financial inclusion, and liquidity risks. Firstly, the structure of the financial market in Ghana suffers from limited infrastructure, which hinders the ability of the banks and other financial intermediaries to operate efficiently and effectively. The lack of efficient payment systems, poor access to financial technology, and inadequate capital markets infrastructure all impede the efficient flow of money and the allocation of credit. As a result, there is a lack of access to capital and resources, which can act as a major constraint on the growth of the market. Financial inclusion is also a major challenge in Ghana. Notably, the country has an extremely large unbanked population, with around 43% of the population estimated to be unbanked. This is due to various factors, such as access to capital, poverty, and a lack of basic financial literacy. To ensure that all citizens have access to the financial market, the government and the regulators encourager greater financial inclusion and that efforts must be made to educate the population about financial services and products.

Finally, liquidity risks are a major challenge for the Ghanaian financial market. The market is characterized by low liquidity and a lack of long-term resources, leading to a reliance on short-term money markets. This poses significant risks, as the market can be vulnerable to sudden changes in liquidity, which can cause rapid and significant downturns in the economy. The structure of Ghana's financial market is thus hampered by various challenges, which affect its ability to provide the efficient credit and capital allocation needed for economic growth and stability. To counter this, the government and the regulators must continue to work to improve the infrastructure of the financial system, promote financial inclusion and provide access to credit to all citizens, and promote long-term resources and enhanced liquidity. Ghana has experienced a turbulent economic landscape in recent years.  These issues have highlighted the need for Ghana to undertake a successful debt restructuring program. Furthermore, the banking sector in particular has suffered from a difficult operating environment and the need for reform processes has become increasingly apparent.

### **2.2 Financial market structure**

The financial market structure (FMS) in Ghana is characterized by a relatively large banking sector, comprising 31 banks, 3 non-bank financial institutions and 5 microfinance institutions (MFI's). Furthermore, the country is served by a nonbank financial system including savings and loans companies, merchant banks,

*Emerging Financial Markets in Ghana and Public Financial Management Crisis Uncertainties… DOI: http://dx.doi.org/10.5772/intechopen.111373*

and insurance and finance houses. The banking sector is governed by the Bank of Ghana (BOG), which is responsible for formulating and implementing monetary and banking regulations. The BOG also serves as the primary regulator and supervisor of the banking sector. The banking sector has experienced a period of consolidation in recent years, with the number of banks decreasing from 37 in 2001 to 31 in 2017. The decreasing number of banks has led to an increased concentration of banking assets in the larger financial institutions. There is also a trend of increasing ownership of banking assets within the banking sector, which could result in a lack of competition and higher prices for banking services [11].

The capital market in Ghana is relatively underdeveloped and is characterized by a low level of activity and limited access to finance from the capital markets. The number of listed companies on the Ghana Stock Exchange (GSE) is also low. As of July 2017, the GSE had a total of 43 listed companies, which is one of the lowest levels for a capital market in Sub-Saharan Africa.


**5. The USH protein complexes**

304 Hearing Loss

adulthood (Goodyear and Richardson, 1999; Goodyear and Richardson, 2003; Goodyear et

The distribution of USH proteins in hair cells vary dramatically from the emergence of stereocilia to their maturation. All USH1 proteins are present either at the tip, the ankle links, the transient lateral links, or the kinociliary links of the stereocilia during the early stage of development. They are then restricted to the tip link and the accessory structures of the tip link, the upper (UTLD) and lower (LTLD) tip link densities, in mature hair cells (Figure 4) (Kussel-Andermann et al., 2000; Senften et al., 2006; Lefevre et al., 2008; Grillet et al., 2009; Bahloul et al., 2010; Caberlotto et al., 2011; Grati and Kachar, 2011). USH2 proteins are localized at the ankle links of the stereocilia (McGee et al., 2006; van Wijk et al., 2006; Michalski et al., 2007; Yang et al., 2010), which is a transient structure existing only during development (Goodyear et al., 2005). Whirlin is also present at the tip of stereocilia in the vestibular and cochlear hair cells all the time (Belyantseva et al., 2005; Delprat et al., 2005; Kikkawa et al., 2005). Clarin-1 was found at the stereocilia on postnatal day 0 (Zallocchi et al., 2009). Besides their location at the stereocilia, some USH proteins were found at the synaptic region of the outer and inner hair cells (Reiners et al., 2005b; van Wijk et al., 2006; Zallocchi et al., 2009), the cell body of the spinal ganglia (Alagramam et al., 2001b; Adato et al., 2002; van Wijk et al., 2006), the supporting cells (Alagramam et al., 2001b; Adato et al., 2005a; Adato et al., 2005b), various nervous fibers (van Wijk et al., 2006), and Reissner's membrane (Wilson et al., 2001; Lagziel et al., 2005). However, these distributions of USH proteins need to be further verified, because the specificity of antibodies used in the studies

In the retina, USH proteins are mainly localized in the photoreceptors (Kremer et al., 2006; Reiners et al., 2006; van Wijk et al., 2006; Liu et al., 2007; Maerker et al., 2008; Yang et al., 2010). The photoreceptor is a highly polarized sensory neuron converting light signals to electrical impulses. It consists of the outer segment, connecting cilium, inner segment, cell body, and synaptic terminus (Figure 4). It contacts Muller cells at the adherens junction (the outer limiting membrane in the retina). Its outer segment is immediately next to the retinal

Compared with the studies in the inner ear, the cellular location of USH proteins is less well defined in the retina. All the USH proteins were once localized in the synaptic ends of photoreceptors (Reiners et al., 2005a; Reiners et al., 2005b; Maerker et al., 2008). However, these results are not conclusive (Williams, 2008; Saihan et al., 2009). They are not supported by the phenotypic analyses in USH mutant mice and the symptom manifestation in USH patients. For instance, ultrastructural abnormalities were not found at the synaptic terminus of photoreceptors in USH mice by electron microscopy (Self et al., 1998; Williams et al., 2009; Yang et al., 2010). No defective ERG waveforms typically resulting from abnormal photoreceptor synaptic transmission have been detected in USH mutant mice (Libby and Steel, 2001; Ball et al., 2003; Libby et al., 2003; Haywood-Watson et al., 2006; McGee et al.,

In addition to the synaptic distribution, MYO7A and SANS were shown to be present around the connecting cilium, harmonin at the outer segment, CDH23 in the inner segment,

were not confirmed in their corresponding mutant mice.

2006; Liu et al., 2007; Yang et al., 2010) or in USH patients.

**4.2 USH proteins in the retina**

pigment epithelium (RPE) cells.

al., 2005).

The indistinguishable symptoms within the same USH clinical type and the similar symptoms across different USH clinical types indicate that various USH proteins probably participate in the same cellular pathway in a broad sense. Among the USH proteins, harmonin, whirlin and SANS possess multiple protein-protein interaction domains and are proposed to be scaffold proteins in multi-protein complexes. Biochemical assays have indeed revealed the existence of their self-interactions and interactions with most of other USH proteins in vitro (Table 2). Interestingly, the in vitro interactions among different USH1 and/or USH2 proteins exist extensively (Table 2). One USH protein is generally able to interact with at least three other USH proteins. In most cases, different regions of the same protein are involved in its binding to different USH proteins (Table 2). Although these interactions have not been individually confirmed in vivo, harmonin, MYO7A, and CDH23 were recently reported to form a ternary complex in hair cells (Bahloul et al., 2010). Based on these findings, it has been hypothesized that USH proteins form an interacting network, an interactome, in both hair cells and photoreceptors (Richardson et al.; Kremer et al., 2006; Reiners et al., 2006; Saihan et al., 2009; Millan et al., 2011).

The above hypothesis is supported by the facts that ablation of one USH protein in mice causes mislocation and/or disappearance of at least one other USH protein in hair cells (Table 3). This phenomenon occurs across USH1 and USH2 proteins. Normal distribution of the three USH2 proteins depends on MYO7A and the distribution of some CDH23 isoform at the tip of the stereocilia relies on GPR98 (Table 3). However, the USH1 and USH2 proteins are present at the different interstereociliary links in hair cells during development. Additionally, different USH proteins are localized at two distinct subcellular locations in

Usher Syndrome: Genes, Proteins, Models, Molecular Mechanisms, and Therapies 307

cen MYO7A/MyTH4-FERM (Wu et al, 2011.;

In hair cells, the normal cellular localization of harmonin requires the presence of all other USH1 proteins, and loss of harmonin seems not to affect the localization of other USH1 proteins (Table 3), indicating that harmonin is dispensable for locating these USH1 proteins to their normal position in cells. In contrast, CDH23 is relatively independent on other USH1 proteins, and its loss results in mislocalization of the two putative scaffold proteins, harmonin and SANS (Table 3). Therefore, CDH23 may play a crucial role in anchoring/tethering USH1

Besides the known USH proteins, many other putative components in the USH complexes has been identified. These components are able to interact with at least one of the USH proteins as shown by biochemical assays. For the currently known USH2-interacting proteins, please see the review (Yang et al., 2011). However, additional experiments are necessary to verify the existence of these putative components in the USH complexes in vivo

PDZ3 Whirlin/PDZ1-PDZ2, PR-PDZ3 (Delprat et al., 2005; Yang et al.,

proteins.  Interactions among USH proteins

and reveal their relationship with USH.

photoreceptors, the PMC and the synapse. Due to these different cellular locations of USH proteins, it is reasonable to propose that more than one USH protein complex exist and they play different but highly related roles in a broad cellular process (Williams, 2008; Yang et al., 2011).

photoreceptors, the PMC and the synapse.

**MYO7A**

**Harmonin**

N-terminus,

**CDH23**

Cytoplasmic

**PCDH15**  Cytoplasmic

PDZ1/2 CDH23/PBMs

Table 2. Interactions among USH proteins

In hair cells, the normal cellular localization of harmonin requires the presence of all other USH1 proteins, and loss of harmonin seems not to affect the localization of other USH1 proteins (Table 3), indicating that harmonin is dispensable for locating these USH1 proteins to their normal position in cells. In contrast, CDH23 is relatively independent on other USH1 proteins, and its loss results in mislocalization of the two putative scaffold proteins, harmonin and SANS (Table 3). Therefore, CDH23 may play a crucial role in anchoring/tethering USH1 proteins. Harmonin and SANS may help hold the USH1 proteins in the complex.

Besides the known USH proteins, many other putative components in the USH complexes has been identified. These components are able to interact with at least one of the USH proteins as shown by biochemical assays. For the currently known USH2-interacting proteins, please see the review (Yang et al., 2011). However, additional experiments are necessary to verify the existence of these putative components in the USH complexes in vivo and reveal their relationship with USH.

+: existence of mislocalization, -: normal localization, +/-, contradictory results

Table 3. Interdependence of USH proteins in hair cells

Usher Syndrome: Genes, Proteins, Models, Molecular Mechanisms, and Therapies 309

The severe and early-onset hearing phenotypes in various USH1 and USH2 mouse models make it relatively easier to decipher the functions of USH complexes in the inner ear than in the retina. The following will focus on the three main cellular processes generally believed to involve the USH complexes. Disruption of these USH functions is thought to be the

During development, at the apex of hair cells, microvilli grow into stereocilia by recruiting more actin filaments. These stereocilia are bundled with transient lateral links and are connected with the kinocilium through kinociliary links. Following the establishment of the planar cell polarity, the kinocilium moves from the center to the periphery of the cell, and the stereocilia elongate differentially. The staircase-shape hair bundle is eventually formed. At the same time, the transient lateral links are gradually substituted by two distinct sets of interstereociliary links. They are the horizontal top connectors and the ankle links, close to the tip and base of the hair bundle, respectively (Figure 4). The tip links emerge, which are fibrous connections between the tip of medium and low stereocilia and the side of the neighboring taller stereocilia (Figure 4). Finally, the stereocilia grow both in length and in width and reach their mature size. In rodent mature cochlear hair cells, the ankle links and the kinociliary links disappear with the regression of the kinocilium (Frolenkov et al., 2004;

CDH23 (Siemens et al., 2004; Lagziel et al., 2005; Michel et al., 2005; Rzadzinska et al., 2005; Lefevre et al., 2008) and PCDH15 (Goodyear et al., 2010; Webb et al., 2011; Lefevre et al., 2008) are localized at the transient lateral links and kinociliary links during early development of hair cells. In their mutant mice, hair bundles are usually splayed into several clumps; kinocilium is mispositioned and disconnected with the hair bundle (Lefevre et al., 2008), indicating that CDH23 and PCDH15, as components of the interstereociliary links, are important for hair bundle cohesion and that loss of the connection between the stereocilia and kinocilium causes the misorientation of the hair bundle. Interestingly, the mutant mouse models of all five USH1 genes share such similar phenotypes. This could be explained by the idea that the five USH1 proteins coordinate in this function. The PST domain of harmonin b binds to and bundles actin filaments (Boeda et al., 2002). MYO7A is a high duty ratio motor, which binds to actin filament strongly. Therefore, these two actinbinding proteins may anchor their interacting partners, CDH23 and PCDH15, to the actin bundle in the stereocilia of hair cells (Table 2). In *Ush1g-/-* mice, cohesion of stereocilia is disrupted. In *Ush1gfl/flMyo7a-cre+/-* mice, whose expression of SANS is disturbed only after birth, the stereocilia stay cohesive (Caberlotto et al., 2011). Therefore, SANS plays a role in stereocilia cohesion during the prenatal period. It may be involved in the organization of

All three USH2 proteins, USH2A, GPR98, and whirlin, are positioned at the ankle links of hair cells. Among these proteins, USH2A and GPR98 probably interact with each other or with some unidentified cell adhesion proteins to form the ankle links. Whirlin interacts with USH2A and GPR98 through the PDZ domain-mediated binding to anchor them at the base of the stereocilia. In the absence of GPR98, the ankle links are missing. Thus far, the

other USH1 proteins through directly interacting with them (Table 2).

**6. Functions of the USH complexes**

molecular mechanisms underlying USH.

Goodyear et al., 2005; Nayak et al., 2007).

**6.1 Hair bundle cohesion**


**Author details**

Anna Walke1,2, Eric Suero Molina2 , Walter Stummer2 and Simone König1 \*

1 Core Unit Proteomics, Interdisciplinary Center for Clinical Research, University of Münster, Münster, Germany

2 Department of Neurosurgery, University Hospital Münster, Münster, Germany

\*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.


**5.1 Attack reconstruction in linear system via filtering by adaptive sliding mode observer**

Consider the linearized system in Eq. (5) with *C x*ð Þ¼ *Cx* and *B x*ð Þ¼ *B*

$$
\dot{\mathbf{x}} = A\mathbf{x} + Bd(t), \quad \mathbf{y} = \mathbf{C}\mathbf{x} + Dd(t) \tag{14}
$$

#### *5.1.1 System's transformation*

Considering system Eq. (14) and assuming assumption (A1) holds, then as show in [29] there exists a matrix *N* ∈ *R*ð Þ� *n*�*p n* such that the square matrix

$$T\_c = \begin{bmatrix} N \\ C \end{bmatrix} \tag{15}$$

is nonsingular and the change of coordinates *x*↦*Tcx* creates, without loss of generality, a new state-space representation *A*0 *; B*0 *;C*0 ð Þ *; D* where

$$A' = T\_{\mathfrak{c}} A T\_{\mathfrak{c}}^{-1}, \quad B' = T\_{\mathfrak{c}} B, \quad \mathbf{C}' = \mathbf{C} T\_{\mathfrak{c}}^{-1} = \begin{bmatrix} \mathbf{0}\_{p \times (n-p)} & I\_{p \times p} \end{bmatrix} \tag{16}$$

After the linear changing of coordinate, the CPS Eq. (14) is rewritten as

$$\begin{aligned} \dot{\mathbf{x}}\_1 &= A\_{11}\mathbf{x}\_1 + A\_{12}\mathbf{x}\_2 + B\_1 d\\ \dot{\mathbf{x}}\_2 &= A\_{21}\mathbf{x}\_1 + A\_{22}\mathbf{x}\_2 + B\_2 d \quad \text{where} \quad A' = \begin{bmatrix} A\_{11} & A\_{12} \\ A\_{21} & A\_{22} \end{bmatrix}, \qquad B' = \begin{bmatrix} B\_1 \\ B\_2 \end{bmatrix} \end{aligned} \quad \text{(17)}$$

with *x*1 ∈*Rn*�*p, x*2 ∈*Rp* , *B*1 ∈*R*ð Þ� *n*�*p m*, *B*2 ∈ *Rp*�*m*, *A*11 ∈ *R*ð Þ� *n*�*p* ð Þ *n*�*p* ,

*A*12 ∈*R*ð Þ� *n*�*p p*, *A*21 ∈*Rp*�ð Þ *n*�*p , A*22 ∈*Rp*�*p*. It is well known that ð Þ *A;C* is observable if and only if ð Þ *A*11*; A*21 is observable [31].

Defining a further change of coordinates *x*1 ¼ *x*1 þ *Lx*2 where *L*∈ Rð Þ� *n*�*p p* is the design matrix, then the system Eq. (17) can be rewritten as

$$\begin{aligned} \dot{\overline{\boldsymbol{\varpi}}}\_{1} &= \tilde{A}\_{11}\overline{\boldsymbol{\varpi}}\_{1} + \tilde{A}\_{12}\underline{\boldsymbol{\varkappa}}\_{2} + \tilde{B}\_{1}d \\ \dot{\underline{\boldsymbol{\omega}}}\_{2} &= \tilde{A}\_{21}\overline{\boldsymbol{\varpi}}\_{1} + \tilde{A}\_{22}\underline{\boldsymbol{\varkappa}}\_{2} + \tilde{B}\_{2}d \end{aligned}, \; \boldsymbol{\mathcal{y}} = \boldsymbol{\varkappa}\_{2} + Dd \tag{18}$$

*5.1.2 Attack observation*

*G*1 ¼

and *As*

*C*2 � *G*1*C*1.

\_ *e* ¼

**11**

2 6 4 2 6 4

A SMO is proposed to reconstruct the attack in order to clean up the measurements and states and to allow the use of clean measurement in the control signal.

*Secure State Estimation and Attack Reconstruction in Cyber-Physical Systems: Sliding Mode…*

where *z* ¼ *col*ð Þ *z*1*; z*21*; z*22 is conformal with the partition of *x* in Eq. (22). In Eq. (23), *υ* is a nonlinear injection signal that depends on *y*2 � *z*22 � � and is used to

> *A*12*b A*22*b A*22*d* � *As*

> > *y*2 � *z*22 � � �

where scalar gain *ρ* will be defined in the sequel, and *η* is a positive design scalar.

**Assumption (A4):** Matrix *sI* � *A*∗ ð Þ is invertible, where *A*∗ ¼ *A* � *BD*�1

Defining *e* ¼ *x* � *z*, then it follows *e* ¼ *col*ð Þ *e*1*;e*21*;e*22 where *e*1 ¼ *x*1 � *z*1,

*A*12*b A*22*b A*22*d* � *As*

33

The first main results, based on the SMO with the fixed-gain injection term, is

Then, as soon as the sliding mode is established in finite time in Eq. (27) on the

**Theorem 1:** Assuming (A3)–(A4) hold and *m*0 . 0 satisfies the condition

� �*e*11 � *A*22*d* � *B*22*D*�1

sliding surface Eq. (28) by means of the injection term Eq. (25) with *ρ* ¼ *m*0*kd* þ k k *D*2 ∞*ld*, the attack *d* is asymptotically estimated as

3 7 5 *D*2*d* þ

2 6 4

are the gain matrices where *A*12*a* ∈ Rð Þ� *n*�*p* ð Þ *p*�*m* , *A*22*a* ∈ Rð Þ� *p*�*m* ð Þ *p*�*m* ,

*A*12*b* ∈ Rð Þ� *n*�*p m*, *A*22*b* ∈ Rð Þ� *p*�*m m*, *A*22*d* ∈ R*m*�*m*, and the matrices *As*

33 ∈ R*m*�*m* are user-selected Hurwitz matrices, while *As*

and by direct substitution from Eqs. (22) and (23) that

2 6 4

3 7 5 *e* �

*υ* ¼ �ð Þ *ρ* þ *η y*2 � *z*22

33

3 7 5*, Gn* ¼

**0**ð Þ� *n*�*p m* **0**ð Þ� *p*�*m m* Im�*m*

� *, ρ, η* . 0 (25)

3 7

5 (24)

22 ∈ Rð Þ� *p*�*m* ð Þ *p*�*m*

2

5*υ* (27)

33 is symmetric nega-

2 6 4

*ey*2 ¼ *y*2 � *z*22 ¼ *e*22 þ *D*2*d* (26)

2 6 4

*B*1 *B*21 *B*22

*ey*2 ¼ *y*2 � *z*22 ¼ **0** (28)

� �*D*2*d, e*11 ¼ *col*ð Þ *e*1*;e*21 (29)

2

3 7 5 *d* þ

**0 0** Im 3 7

2 6 4

*z*\_ ¼ *Az* þ *G*1 *y*1 � *z*21 � � þ *G*2 *y*2 � *z*22 � � � *Gnυ* (23)

Define a (sliding mode) observer for the system Eq. (22) as

induce a sliding motion in the estimation error space, and

3 7 5*, G*2 ¼

*A*12*a A*22*a* � *As*

*DOI: http://dx.doi.org/10.5772/intechopen.88669*

**0***m*�ð Þ *p*�*m*

*e*21 ¼ *x*21 � *z*21, *e*22 ¼ *x*22 � *z*22. It follows

*A*11 **0 0** *A*21*a As*

*A*21*b A*22*c As*

formulated in the following theorem.

k k *ϕ*ð Þ*t* ≤ *m*0*kd, ϕ* ¼ *A*21*b A*22*c*

22 **0**

The idea is to force a sliding motion on

33

22

tive definite. The injection signal *υ*∈ R*m* is defined as

where *A*~11 ¼ *A*11 þ *LA*21*, A*~12 ¼ �*A*11*L* þ *A*12 � *LA*21*L* þ *LA*22 , *B*~1 ¼ *B*1 þ *LB*2, *A*~21 ¼ *A*21, *A*~22 ¼ *A*22 � *A*21*L*, *B*~2 ¼ *B*2. Since ð Þ *A*11*; A*21 is observable, there exist choices of the matrix *L* so that the matrix *A*~11 ¼ *A*11 þ *LA*21 is Hurwitz.

**Assumption (A3):** The attack *d t*ð Þ and its derivative are norm bounded, i.e., k k*d* , *kd* and \_ *d* � � � � � � , *ld* where *kd, ld* . 0 and are known.

Since *p* . *m*, there exists a nonsingular scaling matrix *Q* ∈*Rp*�*p* such that

$$QD = \begin{bmatrix} \mathbf{0}\_{(p-m)\times m} \\ D\_2 \end{bmatrix} \tag{19}$$

where *D*2 ∈*Rm*�*m* is nonsingular. Define *y* as the scaling of the measured outputs *y* according to *y* ¼ *Q y*. Partition the output of the CPS into unpolluted measurements *y*1 ∈ R*p*�*m* and polluted measurements *y*2 ∈ R*m* as

$$\overline{\mathcal{Y}} = \begin{bmatrix} \overline{\mathcal{Y}}\_1 \\ \overline{\mathcal{Y}}\_2 \end{bmatrix} = \begin{bmatrix} Q\_1 \mathbf{x}\_2 \\ Q\_2 \mathbf{x}\_2 + D\_2 d \end{bmatrix} = \mathbf{Q} \mathbf{x}\_2 + \begin{bmatrix} \mathbf{0}\_{(p-m)\times m} \\ D\_2 \end{bmatrix} d \tag{20}$$

Scale state component *x*2 and define *x*2 ¼ *Qx*2. Then Eq. (18) can be rewritten as

$$\begin{aligned} \dot{\overline{\boldsymbol{x}}}\_{1} &= \overline{\boldsymbol{A}}\_{11}\overline{\boldsymbol{x}}\_{1} + \overline{\boldsymbol{A}}\_{12}\overline{\boldsymbol{x}}\_{2} + \overline{\boldsymbol{B}}\_{1}d \\ \dot{\overline{\boldsymbol{x}}}\_{2} &= \overline{\boldsymbol{A}}\_{21}\overline{\boldsymbol{x}}\_{1} + \overline{\boldsymbol{A}}\_{22}\overline{\boldsymbol{x}}\_{2} + \overline{\boldsymbol{B}}\_{2}d \end{aligned}, \; \overline{\boldsymbol{y}} = \overline{\boldsymbol{x}}\_{2} + \begin{bmatrix} \mathbf{0} \\ \boldsymbol{D}\_{2} \end{bmatrix} d \tag{21}$$

where *A*11 ¼ *A*~11, *A*12 ¼ *A*~12*Q*�1 , *B*1 ¼ *B*~1, *A*21 ¼ *QA*~21, *A*22 ¼ *QA*~22*Q*�1 , and *B*2 ¼ *QB*~2. Define *x*2 ¼ *col*ð Þ *x*21*; x*22 , where *x*21 ∈ R*p*�*m* and *x*22 ∈ R*m*. Consequently the system in Eq. (21) can be written in partitioned form as

$$\begin{aligned} \dot{\overline{\boldsymbol{x}}} &= \overline{A}\overline{\boldsymbol{x}} + \overline{B}\boldsymbol{d} \\ \overline{\boldsymbol{y}}\_{1} &= \overline{\mathbf{C}}\_{1}\overline{\mathbf{x}}, \; \overline{\boldsymbol{y}}\_{2} = \overline{\mathbf{C}}\_{2}\overline{\mathbf{x}} + D\_{2}\boldsymbol{d} \\ \overline{\boldsymbol{C}}\_{1} &= \begin{bmatrix} \overline{\mathbf{C}}\_{1} \\ \overline{\mathbf{x}}\_{21} \\ \overline{\mathbf{x}}\_{22} \end{bmatrix}, \overline{\boldsymbol{A}} = \begin{bmatrix} \overline{A}\_{11} & \overline{A}\_{12a} & \overline{A}\_{12b} \\ \overline{A}\_{21a} & \overline{A}\_{22a} & \overline{A}\_{22b} \\ \overline{A}\_{21b} & \overline{A}\_{22c} & \overline{A}\_{22d} \end{bmatrix}, \overline{\boldsymbol{B}} = \begin{bmatrix} \overline{B}\_{1} \\ \overline{B}\_{21} \\ \overline{B}\_{21} \end{bmatrix} \end{aligned} \tag{21}$$

where *A*11 is Hurwitz and the virtual measurement *y*1 presents the protected measurements and *y*2 shows the attacked/corrupted measurements.

*Secure State Estimation and Attack Reconstruction in Cyber-Physical Systems: Sliding Mode… DOI: http://dx.doi.org/10.5772/intechopen.88669*

#### *5.1.2 Attack observation*

*x*\_ 1 ¼ *A*11*x*1 þ *A*12*x*2 þ *B*1*d x*\_ 2 ¼ *A*21*x*1 þ *A*22*x*2 þ *B*2*d*

*Control Theory in Engineering*

and only if ð Þ *A*11*; A*21 is observable [31].

*where A*0 ¼

with *x*1 ∈*Rn*�*p, x*2 ∈*Rp* , *B*1 ∈*R*ð Þ� *n*�*p m*, *B*2 ∈ *Rp*�*m*, *A*11 ∈ *R*ð Þ� *n*�*p* ð Þ *n*�*p* ,

*x*\_ 1 ¼ *A*~ 11*x*1 þ *A*~ 12*x*2 þ *B*~1*d*

choices of the matrix *L* so that the matrix *A*~11 ¼ *A*11 þ *LA*21 is Hurwitz.

design matrix, then the system Eq. (17) can be rewritten as

ments *y*1 ∈ R*p*�*m* and polluted measurements *y*2 ∈ R*m* as

¼ *Q*1*x*2 *Q*2*x*2 þ *D*2*d* � �

*x*\_ 1 ¼ *A*11*x*1 þ *A*12*x*2 þ *B*1*d*

the system in Eq. (21) can be written in partitioned form as

*, x* ¼

measurements and *y*2 shows the attacked/corrupted measurements.

*C*1 ¼ **0**ð Þ� *p*�*m* ð Þ *n*�*p I*ð Þ� *p*�*m* ð Þ *p*�*m* **0**ð Þ� *p*�*m m*

*x*\_ 2 ¼ *A*21*x*1 þ *A*22*x*2 þ *B*2*d , y* ¼ *x*2 þ

*x*1

*x*21

*x*22

*B*2 ¼ *QB*~2. Define *x*2 ¼ *col*ð Þ *x*21*; x*22 , where *x*21 ∈ R*p*�*m* and *x*22 ∈ R*m*. Consequently

3 7 7 7 5*, A* ¼

� �*, C*2 ¼ **0***m*�ð Þ *n*�*m Im*�*m*

where *A*11 is Hurwitz and the virtual measurement *y*1 presents the protected

*A*12 ∈*R*ð Þ� *n*�*p p*, *A*21 ∈*Rp*�ð Þ *n*�*p , A*22 ∈*Rp*�*p*. It is well known that ð Þ *A;C* is observable if

where *A*~11 ¼ *A*11 þ *LA*21*, A*~12 ¼ �*A*11*L* þ *A*12 � *LA*21*L* þ *LA*22 , *B*~1 ¼ *B*1 þ *LB*2, *A*~21 ¼ *A*21, *A*~22 ¼ *A*22 � *A*21*L*, *B*~2 ¼ *B*2. Since ð Þ *A*11*; A*21 is observable, there exist

**Assumption (A3):** The attack *d t*ð Þ and its derivative are norm bounded, i.e.,

*QD* ¼ **0**ð Þ� *p*�*m m*

*D*2 � �

¼ *Qx*2 þ

**0**ð Þ� *p*�*m m D*2 � �

> **0** *D*2

, *B*1 ¼ *B*~1, *A*21 ¼ *QA*~21, *A*22 ¼ *QA*~22*Q*�1

*A*11 *A*12*a A*12*b*

*A*21*a A*22*a A*22*b*

*A*21*b A*22*c A*22*d*

" #

where *D*2 ∈*Rm*�*m* is nonsingular. Define *y* as the scaling of the measured outputs *y* according to *y* ¼ *Q y*. Partition the output of the CPS into unpolluted measure-

Scale state component *x*2 and define *x*2 ¼ *Qx*2. Then Eq. (18) can be rewritten as

, *ld* where *kd, ld* . 0 and are known. Since *p* . *m*, there exists a nonsingular scaling matrix *Q* ∈*Rp*�*p* such that

Defining a further change of coordinates *x*1 ¼ *x*1 þ *Lx*2 where *L*∈ Rð Þ� *n*�*p p* is the

*A*11 *A*12

" #

*A*21 *A*22

*x*\_ 2 ¼ *A*~ 21*x*1 þ *A*~ 22*x*2 þ *B*~2*d , y* ¼ *x*2 þ *Dd* (18)

*, B*0 ¼

*B*1

(17)

(19)

*d* (20)

*d* (21)

3 7 7 7 5*, B* ¼

� �

, and

*B*1

*B*21

*B*22

(22)

" #

*B*2

*y* ¼ *x*2 þ *Dd*

k k*d* , *kd* and \_

*d* � � � � � �

*y* ¼ *y*1 *y*2 � �

where *A*11 ¼ *A*~11, *A*12 ¼ *A*~12*Q*�1

*y*1 ¼ *C*1*x, y*2 ¼ *C*2*x* þ *D*2*d*

*x*\_ ¼ *Ax* þ *Bd*

**10**

A SMO is proposed to reconstruct the attack in order to clean up the measurements and states and to allow the use of clean measurement in the control signal. Define a (sliding mode) observer for the system Eq. (22) as

$$\dot{\overline{z}} = \overline{A}\overline{z} + \overline{G}\_1(\overline{y}\_1 - \overline{z}\_{21}) + \overline{G}\_2(\overline{y}\_2 - \overline{z}\_{22}) - G\_n \nu \tag{23}$$

where *z* ¼ *col*ð Þ *z*1*; z*21*; z*22 is conformal with the partition of *x* in Eq. (22). In Eq. (23), *υ* is a nonlinear injection signal that depends on *y*2 � *z*22 � � and is used to induce a sliding motion in the estimation error space, and

$$
\overline{\mathbf{G}}\_1 = \begin{bmatrix} \overline{A}\_{12a} \\ \overline{A}\_{22a} - A\_{22}^s \\ \mathbf{0}\_{m \times (p-m)} \end{bmatrix}, \overline{\mathbf{G}}\_2 = \begin{bmatrix} \overline{A}\_{12b} \\ \overline{A}\_{22b} \\ \overline{A}\_{22d} - A\_{33}^s \end{bmatrix}, \mathbf{G}\_n = \begin{bmatrix} \mathbf{0}\_{(n-p)\times m} \\ \mathbf{0}\_{(p-m)\times m} \\ \mathbf{I}\_{m\times m} \end{bmatrix} \tag{24}
$$

are the gain matrices where *A*12*a* ∈ Rð Þ� *n*�*p* ð Þ *p*�*m* , *A*22*a* ∈ Rð Þ� *p*�*m* ð Þ *p*�*m* , *A*12*b* ∈ Rð Þ� *n*�*p m*, *A*22*b* ∈ Rð Þ� *p*�*m m*, *A*22*d* ∈ R*m*�*m*, and the matrices *As* 22 ∈ Rð Þ� *p*�*m* ð Þ *p*�*m* and *As* 33 ∈ R*m*�*m* are user-selected Hurwitz matrices, while *As* 33 is symmetric negative definite. The injection signal *υ*∈ R*m* is defined as

$$\rho = -(\rho + \eta) \frac{\overline{y}\_2 - \overline{z}\_{22}}{||\overline{y}\_2 - \overline{z}\_{22}||}, \quad \rho, \eta > 0 \tag{25}$$

where scalar gain *ρ* will be defined in the sequel, and *η* is a positive design scalar. **Assumption (A4):** Matrix *sI* � *A*∗ ð Þ is invertible, where *A*∗ ¼ *A* � *BD*�1 2 *C*2 � *G*1*C*1.

Defining *e* ¼ *x* � *z*, then it follows *e* ¼ *col*ð Þ *e*1*;e*21*;e*22 where *e*1 ¼ *x*1 � *z*1, *e*21 ¼ *x*21 � *z*21, *e*22 ¼ *x*22 � *z*22. It follows

$$
\overline{\mathbf{z}}\_{\mathcal{V}\_{2}} = \overline{\mathbf{y}}\_{2} - \overline{\mathbf{z}}\_{22} = \overline{\mathbf{c}}\_{22} + D\_{2}d \tag{26}
$$

and by direct substitution from Eqs. (22) and (23) that

$$
\dot{\overline{e}} = \begin{bmatrix} \overline{A}\_{11} & \mathbf{0} & \mathbf{0} \\ \overline{A}\_{21a} & A\_{22}^{\circ} & \mathbf{0} \\ \overline{A}\_{21b} & \overline{A}\_{22c} & A\_{33}^{\circ} \end{bmatrix} \overline{e} - \begin{bmatrix} \overline{A}\_{12b} \\ \overline{A}\_{22b} \\ \overline{A}\_{22d} - A\_{33}^{\circ} \end{bmatrix} D\_2 d + \begin{bmatrix} \overline{B}\_1 \\ \overline{B}\_{21} \\ \overline{B}\_{22} \end{bmatrix} d + \begin{bmatrix} \mathbf{0} \\ \mathbf{0} \\ \mathbf{I}\_m \end{bmatrix} \nu \tag{27}
$$

The idea is to force a sliding motion on

$$
\mathbf{e}\_{\mathcal{V}\_2} = \overline{\mathbf{y}}\_2 - \overline{\mathbf{z}}\_{22} = \mathbf{0} \tag{28}
$$

The first main results, based on the SMO with the fixed-gain injection term, is formulated in the following theorem.

**Theorem 1:** Assuming (A3)–(A4) hold and *m*0 . 0 satisfies the condition

$$\|\|\phi(t)\|\| \le m\_0 k\_d, \quad \phi = \begin{bmatrix} \overline{A}\_{21b} & \overline{A}\_{22c} \end{bmatrix} \overline{e}\_{11} - \begin{pmatrix} \overline{A}\_{22d} - \overline{B}\_{22} D\_2^{-1} \end{pmatrix} D\_2 d, \quad \overline{e}\_{11} = \text{col}(\overline{e}\_1, \overline{e}\_{21}) \tag{29}$$

Then, as soon as the sliding mode is established in finite time in Eq. (27) on the sliding surface Eq. (28) by means of the injection term Eq. (25) with *ρ* ¼ *m*0*kd* þ k k *D*2 ∞*ld*, the attack *d* is asymptotically estimated as

$$\hat{d} = G^\*(s)\boldsymbol{\nu}\_{\boldsymbol{q}} \quad \text{where} \quad G^\*\left(\boldsymbol{s}\right) = \mathbf{C}^\*\left(\boldsymbol{s}\boldsymbol{I} - \boldsymbol{A}^\*\right)^{-1}\boldsymbol{B}^\*, \ \boldsymbol{B}^\* = \begin{bmatrix} \mathbf{0}\_{\left(\boldsymbol{n}-\boldsymbol{p}\right)\times\boldsymbol{m}} \\ \mathbf{0}\_{\left(\boldsymbol{p}-\boldsymbol{m}\right)\times\boldsymbol{m}} \\ \boldsymbol{I}\_{\boldsymbol{m}\times\boldsymbol{m}} \end{bmatrix}, \boldsymbol{\mathcal{C}}^\* = \begin{bmatrix} \mathbf{0}\_{\boldsymbol{m}\times\left(\boldsymbol{n}-\boldsymbol{m}\right)} & -\boldsymbol{D}\_2^{-1} \end{bmatrix} \tag{30}$$

where *υeq* is the *equivalent* injection term [31] and a close approximation and *υeq* can be obtained in real time by low-pass filtering of the switching signal Eq. (25) [29]. Replacing *υeq* by *υeq* in Eq. (30) gives

$$
\hat{d} = G^\*(\mathfrak{s}) \overline{\mathfrak{v}}\_{eq} \tag{31}
$$

ℓ\_ðÞ¼ *t γ σ*j j ð Þ*t if*j j *σ*ð Þ*t* . *σ*0 0 *otherwise*

*Secure State Estimation and Attack Reconstruction in Cyber-Physical Systems: Sliding Mode…*

**Theorem 2:** Consider the system in Eq. (27) and

*a t*ðÞ¼ *As*

1 4 *ε*2 . *σ*2

in Theorem 2 as:

k k*d* , *kd* and \_

*r* ¼ *r*1*;r*2*;* …*;rp*1

*5.2.1 Attack observation*

**13**

**twisting SMO**

*d* , *ld*.

If *ε* . 0 in (34) is chosen to satisfy

*DOI: http://dx.doi.org/10.5772/intechopen.88669*

equivalent adaptive injection term *υeq* or *υeq*.

*C*1ð Þ¼ *x C*1*x*, *C*2ð Þ¼ *x C*2*x*, *B*1ð Þ¼ *x B*, that is,

where *B*1 ∈ R*n*�*m*1 , *C*1 ∈ Rð *p*�ð Þ *m*�*m*1 Þ�*n*, *C*2 ∈ Rð Þ� *m*�*m*1 *n*.

*C*1*iAj*

*C*1*iAri*�1

**Assumption (A6):** there exists a full rank matrix.

Without loss of generality, it is assumed that *r*1 ≤ … ≤*rp*1

*B*1 6¼ 0

where *γ* . 0*, σ*0 . 0 are design scalars. The second main results are summarized

and assume that j j *a t*ð Þ , *a*0*,* j j *a t* \_ð Þ , *a*1, where *a*0 and *a*1 are finite but unknown. A SMO is designed as in Eq. (23) with the *adaptive* injection term in Eqs. (32)–(37).

> 0 þ 1 *γ*

for any given *σ*0, *q* . 1, and, 0 , *α* , 1, then the injection term (32) exploiting the *dual layer adaptive* scheme given by Eqs. (35)–(37) drives *σ*ð Þ*t* to a domain j j *σ*ð Þ*t* , *ε=*2 in finite time and consequently ensures a sliding motion *ey* ¼ 0 can be reached in finite time and sustained thereafter. The gains *r t*ð Þ and *ρ*ð Þ*t* remain bounded. The sensor attack signal *d t*ð Þ is reconstructed as in Eq. (30) with the

Proof of Theorem 2 is based on the results in [32] and is omitted for brevity. **Remark 2:** The proposed unit vector injection gain-adaptation algorithm in Eqs. (32)–(37) does not require the knowledge of the boundaries *kd, ld* . 0 in

**5.2 State estimation and attack reconstruction in linear systems by using super**

**Assumption (A5):** The number of uncorrupted/protected measurements is equal or larger than the number of state/plant attack, i.e., *p*1 ¼ *p* � ð Þ *m* � *m*1 ≥ *m*1. The system Eq. (40) is assumed to have an input-output vector relative degree

, where *relative degree ri* for *i* ¼ 1*,* 2*,* …*, p*1 is defined as follows:

*B*1 ¼ 0 *for all j* , *ri* � 1

.

*x*\_ ¼ *Ax* þ *B*1*dx*ð Þ*t , y*1 ¼ *C*1*x , y*2 ¼ *C*2*x* þ *D*1*dy*ð Þ*t* (40)

Consider the completely observable linearized system Eq. (11) with

33*ey*2 þ *ϕ* þ *D*2 \_

*qa*1 *α* 2 (37)

(39)

(41)

*d* (38)

Proof of the Theorem 1 is omitted for brevity.

**Remark 1:** The SMO (31) is a dynamic filter that allows reconstructing the time-varying attack *d t*ð Þ. This filter is the main novel feature of the proposed observer.

#### *5.1.3 Adaptive-gain attack observer design*

In Eq. (29), it was assumed that the perturbation term *φ* is locally normbounded and *ρ* . 0 in Eq. (25) is known. In many practical cases, the boundary of attacks is unknown, and the gain of the sliding mode injection term Eq. (25) in the fixed-gain observer in Eq. (23) can be overestimated. The gain overestimation could increase chattering that is difficult to attenuate.

The constant gain *ρ* . 0 can be replaced by an adaptive-gain *ρ*ð Þ*t* by applying the *dual layer nested adaptive sliding mode observation algorithm* [32], i.e.,

$$\rho = - (\rho(t) + \eta) \frac{\overline{\mathcal{Y}}\_2 - \overline{\varpi}\_{22}}{||\overline{\mathcal{Y}}\_2 - \overline{\varpi}\_{22}||} \tag{32}$$

A sufficient condition to ensure sliding on *ey*2 ¼ **0** in finite time is

$$\rho(t) \ge \left\| A^s\_{33} e\_{\mathbb{V}\_2} + \phi + D\_2 \dot{d} \right\|\tag{33}$$

An error signal is defined as

$$
\sigma(t) = \rho(t) - \frac{1}{a} \left| \left| \overline{v}\_{eq}(t) \right| \right| - \varepsilon \tag{34}
$$

where the scalars 0 , *α* , 1, *ε* . 0. The adaptation dynamics of *ρ*ð Þ*t* in Eq. (32) is defined as [32].

$$\dot{\rho}(t) = -r(t)\text{sign}(\sigma(t))\tag{35}$$

where the time-varying scalar *r t*ð Þ . 0 satisfies an adaptive scheme. It is assumed that *r t*ð Þ has the structure

$$r(t) = \ell\_0 + \ell(t) \tag{36}$$

where ℓ0 is a fixed positive scalar. The evolution of ℓð Þ*t* is chosen to satisfy an adaptive law [32]:

*Secure State Estimation and Attack Reconstruction in Cyber-Physical Systems: Sliding Mode… DOI: http://dx.doi.org/10.5772/intechopen.88669*

$$\dot{\boldsymbol{\varepsilon}}^{\dot{\varepsilon}}(t) = \begin{cases} \boldsymbol{\gamma}|\sigma(t)| & \dot{\boldsymbol{\varepsilon}}^{\boldsymbol{\varepsilon}}|\sigma(t)| \ge \sigma\_0 \\ \mathbf{0} & \text{otherwise} \end{cases} \tag{37}$$

where *γ* . 0*, σ*0 . 0 are design scalars. The second main results are summarized in Theorem 2 as:

**Theorem 2:** Consider the system in Eq. (27) and

^

observer.

*d* ¼ *G*∗ ð Þ*s υeq where G*∗ ðÞ¼ *s C*∗ *sI* � *A*∗ ð Þ�1

*Control Theory in Engineering*

[29]. Replacing *υeq* by *υeq* in Eq. (30) gives

*5.1.3 Adaptive-gain attack observer design*

An error signal is defined as

defined as [32].

that *r t*ð Þ has the structure

adaptive law [32]:

**12**

increase chattering that is difficult to attenuate.

Proof of the Theorem 1 is omitted for brevity.

*B*∗ *, B*∗ ¼

where *υeq* is the *equivalent* injection term [31] and a close approximation and *υeq* can be obtained in real time by low-pass filtering of the switching signal Eq. (25)

^

**Remark 1:** The SMO (31) is a dynamic filter that allows reconstructing the time-varying attack *d t*ð Þ. This filter is the main novel feature of the proposed

In Eq. (29), it was assumed that the perturbation term *φ* is locally normbounded and *ρ* . 0 in Eq. (25) is known. In many practical cases, the boundary of attacks is unknown, and the gain of the sliding mode injection term Eq. (25) in the fixed-gain observer in Eq. (23) can be overestimated. The gain overestimation could

*dual layer nested adaptive sliding mode observation algorithm* [32], i.e.,

A sufficient condition to ensure sliding on *ey*2 ¼ **0** in finite time is

� � �

*ρ*ð Þ*t* . *As*

*σ*ðÞ¼ *t ρ*ðÞ�*t*

The constant gain *ρ* . 0 can be replaced by an adaptive-gain *ρ*ð Þ*t* by applying the

*y*2 � *z*22 � � � �

*d*

� �

*ρ*\_ðÞ¼� *t r t*ð Þ*sign*ð Þ *σ*ð Þ*t* (35)

*r t*ðÞ¼ ℓ0 þ ℓð Þ*t* (36)

� (33)

� � *ε* (34)

33*ey*2 þ *ϕ* þ *D*2 \_

1 *α υeq*ð Þ*t* � � �

where the scalars 0 , *α* , 1, *ε* . 0. The adaptation dynamics of *ρ*ð Þ*t* in Eq. (32) is

where the time-varying scalar *r t*ð Þ . 0 satisfies an adaptive scheme. It is assumed

where ℓ0 is a fixed positive scalar. The evolution of ℓð Þ*t* is chosen to satisfy an

*υ* ¼ �ð Þ *ρ*ð Þþ*t η y*2 � *z*22

**0**ð Þ� *n*�*p m* **0**ð Þ� *p*�*m m Im*�*m*

*d* ¼ *G*∗ ð Þ*s υeq* (31)

*, C*∗ ¼ **0***m*�ð Þ *n*�*m* �*D*�1

� �

2

(30)

(32)

$$\mathfrak{a}(t) = A\_{33}^s \mathfrak{e}\_{\mathfrak{P}\_2} + \phi + D\_2 \dot{d} \tag{38}$$

and assume that j j *a t*ð Þ , *a*0*,* j j *a t* \_ð Þ , *a*1, where *a*0 and *a*1 are finite but unknown. A SMO is designed as in Eq. (23) with the *adaptive* injection term in Eqs. (32)–(37). If *ε* . 0 in (34) is chosen to satisfy

$$\frac{1}{4}\varepsilon^2 > \sigma\_0^2 + \frac{1}{\chi} \left(\frac{qa\_1}{a}\right)^2\tag{39}$$

for any given *σ*0, *q* . 1, and, 0 , *α* , 1, then the injection term (32) exploiting the *dual layer adaptive* scheme given by Eqs. (35)–(37) drives *σ*ð Þ*t* to a domain j j *σ*ð Þ*t* , *ε=*2 in finite time and consequently ensures a sliding motion *ey* ¼ 0 can be reached in finite time and sustained thereafter. The gains *r t*ð Þ and *ρ*ð Þ*t* remain bounded. The sensor attack signal *d t*ð Þ is reconstructed as in Eq. (30) with the equivalent adaptive injection term *υeq* or *υeq*.

Proof of Theorem 2 is based on the results in [32] and is omitted for brevity.

**Remark 2:** The proposed unit vector injection gain-adaptation algorithm in Eqs. (32)–(37) does not require the knowledge of the boundaries *kd, ld* . 0 in k k*d* , *kd* and \_ *d* , *ld*.


**Part 3**

**Bacterial Bioluminescence**

164 Bioluminescence – Recent Advances in Oceanic Measurements and Laboratory Applications

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**8**

*Japan*

Satoshi Sasaki

*Tokyo University of Technology*

**Oscillation in Bacterial Bioluminescence**

Live cells show various dynamic characteristics, such as cell division or material production. When we consider that a cell is a chemical reactor that contains an enzyme in its structure, the rates of chemical reaction catalysed by them depend on the cell density. As the amount of enzyme within the cell differs according to the rate of expression of a specific gene, the rate of the reaction also depends on the condition of the cell. In short, chemical reactions caused by cells are nonlinearly related to the cell density; the reaction rate is not proportional to the cell density. This is one remarkable aspect of live cells. In the field of chemical analysis, bacterial cell behaviour is often used. For example, changes in respiration caused by chemical compounds that inhibit the respiratory chain (such as KCN) can be quantified, theoretically, by measuring the changes in the dissolved oxygen concentration. Biomaterial-based devices have been reported, such as biochips or biosensors. These are not truly "bio" because they use an enzyme or antibody outside of the cell. Microbial sensors (Melidis, P.; Georgiou, D.(2002).; Kang. KH.; Jang. JK.; Pham. TH.; Moon. H.; Chang. IS. & Kim, BH. (2003).; Moon, H.; Chang, IS.; Kang, KH.; Jang, JK. & Kim, BH. (2004). ; Chang, IS.; Moon, H.; Jang, JK. & Kim, BH. (2005).; Kogure, H.; Kawasaki, S.; Nakajima, K.; Sakai, N.; Futase, K.; Inatsu, Y.; Bari, ML.; Isshiki, K. & Kawamoto, S. (2005).; Vaiopoulou, E.; Melidis, P.; Kampragou, E. & Aivasidis, A. (2004).; Yano, Y.; Numata, M.; Hachiya, H.; Ito, S.; Masadome, T.; Ohkubo, S.; Asano, Y. & Imato, T. (2001).; Kim, M.; Hyun, MS.; Gadd, GM.; Kim, GT.; Lee, SJ. & Kim, HJ. (2009). Davila, D.; Esquivel, JP.; Sabate, N. & Mas, J. (2011).), known as the analysis of devices that use live microbial cells as molecular-recognition material, are the only exception. This sensor, however, is based on a shift from one equilibrium to another. For example, a respiration inhibition-based microbial sensor measures a certain toxic compound because the dissolved oxygen concentration near the cells increases when the toxic compound exists. The main reason for the use of microorganisms is that they are more cost-effective than purified enzymes or antibodies. The dynamics of the bacterial cells are not at all used. The nonlinearity of cell behaviour has recently been studied (Wu, BM.; Subbarao, KV. & Qin, QM. (2008).; Kenkre, V. M.; &, Kumar, N. (2008).; Dobrescu, R. & Purcarea, VI. (2011)). A suitable bacterium model is, therefore, needed to start a fundamental study on the nonlinearity of the cell. In our group studies, bioluminescence characteristics have been identified (Sasaki S., Mori Y., Ogawa M., Funatsuka S.,(2010)). Bioluminescent bacteria are those that emit light autonomously without the need of excitation light. The bioluminescence reaction is catalysed by bacterial

**1. Introduction**


3.1.3. Chloroflexi

Genes for the synthesis of ectoine and betaine were not found in the *Chloroflexus* and *Roseiflexus* species (Table 1). Additionally, transport systems for osmotica are absent from the *Chloroflexus* species, which characterizes them as strict freshwater bacteria. An ABC transport system (annotated as *opuCBproXV* and an ABC transport protein) found in the *Roseiflexus castenholzii* and *Roseiflexus* species RS-1 (Table 1) might as well represent an ancient evolutionary form of osmolyte transport and betaine uptake from the environment. Thereby, the *Roseiflexus* species might gain limited possibility for osmotic adaptation. As these bacteria are among the oldest mat-forming phototrophic bacteria and *Roseiflexus* might be able to take up betaine or other osmolytes, they or relatives thereof are expected to be found in marine microbial mats. It would be interesting to see, whether marine relatives have possibilities of compatible solute biosynthesis. The species known and characterized so far are expected to have lost such possibilities.

## 3.1.4. Marine Rhizobiales

Freshwater *Rhizobiales*(species of *Rhodoblastus*, *Rhodopseudomonas*, *Blastochloris*, *Rhodomicrobium*, and *Rhodoplanes*) lack both, biosynthesis genes for ectoine and betaine (from choline and glycine) as well as transport systems for these osmolytes (Table 2). In a group of marine *Rhizobiales* (*Fulvimarina pelagi, Hoeflea phototrophica, Rhodobium orientis, Afifella* species), the choline-dependent biosynthesis of betaine (BetABI) and a BetT transporter are present (Table 2). In addition, one or more copies/versions of the ProU system are found. Therefore, osmotic adaptation of these bacteria to the marine environment can be achieved by uptake of betaine or choline. In the absence of these compounds in the environment, other compatible solutes might be accumulated. For *Afifella marina* (formerly *Rhodopseudomonas marina*), the accumulation of trehalose was demonstrated [12].

#### 3.1.5. Marine and Halotolerant Rhodobacteraceae

The *Rhodobacteraceae* include freshwater, marine and halophilic species. With the exception of the freshwater *Rhodobacter* species, all of them have a complete gene cluster for ectoine biosynthesis (*ectRectABCask-ect*). In addition, the extremely halotolerant *Roseivivax halodurans*, *Roseivivax roseus*, *Rhodosalinus sediminis*, and *Roseovarius nitratireducens* (not *Roseivivax halotolerans* and *Roseovarius halotolerans*) have genes of betaine biosynthesis from

glycine, with gene clusters of varying composition (Table 2). In these bacteria, the GMT and DMT methyltransferase genes are fused, as in some of the halophilic *Rhodospirillaceae* (see below). Most of the *Rhodobacteraceae* have several transport systems for osmolytes. All have the BetT transport system, some strains have multiple copies. With the exception of *Rhodobaculum claviforme* and *Rhodovulum imhoffii*, they have several ProU systems, which according to the ProW sequences are phylogenetically distinct (Table 2 and see below under Section 3.5).


2.5.4. Permeability Tests

The water vapor permeability (WVP) of the film samples was determined using the gravimetric method ASTM E96-95 in triplicate. For this, 5 mL of distilled water was placed inside a Payne permeability cup (diameter of 3.5 cm) from Elcometer Sprl (Hermallesous-Argenteau, Belgium). The films were not in direct contact with water but exposed to 100% RH on one side and secured with silicon rings. The samples were placed within a desiccator, filled with dried silica gel, at 0% RH and 25 ◦C. The control samples were cups with aluminum films to estimate the solvent loss through the sealing and samples placed in cups but without permeant to compensate for mass losses due to eugenol release. The cups were weighted periodically using an analytical balance ( ±0.0001 g). WVP was calculated from the regression analysis of weight loss data vs. time and the weight loss was compensated by the marginal losses through the sealing and eugenol release. The permeability was obtained by multiplying the permeance by the film thickness.

Similar as described above for WVP, limonene permeability (LP) was measured placing 5 mL of D-limonene inside the Payne permeability cups. The cups containing the films were placed at the controlled room conditions of 25 ◦C and 40% RH. The samples were measured in triplicate and the limonene vapor permeation rate (LPRT) values were estimated from the steady-state permeation slopes and the weight loss was compensated by the comparatively marginal loss through the sealing and by the fluctuations in mass of the films due to eugenol evaporation and potential water sorption. LP was calculated taking into account the average film thickness in each case.


"kurčenje".15 In the song 'What (kurčenje again)',16 she raps: "I don't want an opinion, but rather an attitude, enough dithering, I'm sick of weighing, sick of whining" (Neću mišljenje već STAV, dosta je dvoumljenja/ Dosta mi je vaganja, dosta prenemaganja); the song 'Kurčenje is a must' ('Kurčiti se mora'), nails down such an attitude by proclaiming that the "First rule of hardcore is that kurčenje is a must, why be a good girl, when that's boring as hell" (Prvo pravilo hardkora je da kurčiti se mora/ šta ti vredi što si dobra kada nema većeg smora).17 The empowered woman that we see is someone who possesses certain traditionally masculine traits, refusing to adapt to gender stereotypes, but who uses social expectations of women to advance her own agenda and obtain material wealth. In a number of songs from the early stages of her career, she addresses the perceived stupidity of men who are ready to pay for sex or to watch a woman undress.  The construction of such an empowered figure enables Mimi to turn the conceptions of femininity which have traditionally been seen as objectifying towards female bodies (and thus hurting their social image) into a source of strength and pride. In other words, she embraces the negative stereotypes about women, and turns them into positive traits and signs of empowerment.18 This persona is, additionally, built up into a leader (or a representative) of a generation of young people and an idol for girls (and boys) trying to find their way through the disaster capitalism that took its roots in postsocialist Serbia.

15 The word is a vulgar term for an attitude of showing off and boasting about one's power, money, intellect or other desirable traits. The root of the word is a swear-word for penis, turned into a verb, so it can also be understood as referring to men boasting their sexual prowess. However, it is used to describe the behavior of both men and women. Mimi Mercedez refers to it explicitly in two of her songs: 'Šta (opet neko kurčenje)' and 'Kurčiti se mora', but also her other songs and public appearances resonate with the attitude described in these songs.

16 This is a loose translation of the original, 'Šta (opet neko kurčenje)'.

17 "Hardcore" is a term often used by Mimi Mercedez, as well as other artists from this circle. It mainly refers to a lifestyle in which everything one does is pushed to the extreme: constant partying, doing a lot of drugs and having a lot of sex, being rude and obnoxious, not letting anyone dictate your life, etc.

18 This mechanism is not something typical only for Mimi Mercedez, but a strategy often used by different subcultures or identity groups, where a word, label or a concept with negative connotation is appropriated and renegotiated, infused with different meaning. It is a strategy analyzed in great detail by many authors, including Judith Butler and José Esteban Muñoz, who used the term disidentification to explain it. Given its complexity, I chose not to dive deeper into the analysis of the phenomenon.

### **(Anti) Heroine**

In this chapter, I use the terms like "leader" or "leadership" to refer to various different things and attitudes. However, they are all related to the figure of an empowered woman whois, asitis commonin neoliberal contexts, working towards empowering others through "leading by example", to use a commonidiom. In the case ofMimiMercedez's songs, her position of strength within the hip hop/trap scene depends on the fact that she is a woman among men. In the song 'True Lady' ('Prava dama', 2016), she mentions "a bunch of rappers in diapers", noting that she is "a young mother", who has no issues in "raising them all by myself " [Brda repera u pelenama ja sam mlada mama/ Cimam se bez blama da ih sve odgajim sama]. In "Porno", she raps that everyone is hot for the girl, because the girl kicks ass ("Sad svi lože se na klinku jer klinka kida"), and continues remarking that everyone thinks that she works in the "oldest trade" (referring to prostitution) when she says that she isn't happy with minimum wage, alluding to various waves of moral panic from the public that followed her appearances, deemed as being sexually explicit, and therefore problematic.19

What makes such an empowered attitude specific, is the local, postsocialist context in which it is formulated, with the woman presenting herself as the leader/representative of a generation, also representing an antiheroine, a symptom of a failed society ruined by postsocialist transition. Specificities of that context have been discussed by a large number of authors since the fall of the Berlin wall, with most of them focusing on "the disastrous consequences of the introduction of neoliberal capitalism and the deep socioeconomic transformation this entailed, resulting in drastic inequalities between a tiny layer of the newly rich, diminishing middle class and the increasingly populous poor strata" (Horvat and Štiks 2015: 23). In other words, the generation that Mimi Mercedez represents (as she said in the interview quoted earlier), is a generation that grew up in a society which saw the steady privatization of all public resources, healthcare and education, a generation that witnessed their parents losing their jobs because the once stateowned companies were ruined and sold to foreign investors, and whose future lies (generally speaking) in finding a way to earn a lot of money quickly,in being a source of cheap, yet well-educated labor, or emigrating. In addition, in such postsocialist societies, success – equated mainly with material prosperity – is attributed solely to one's individual strengths and qualities, or as Mimi raps in the song 'I Have No Strength'('Nemam Snage', 2016): "I want to be in control, I want to be the boss, and this is why I want to be rich and famous". Postsocialism is, thus, the context that is criticized by Mimi Mercedez, by constructing herself as a representative of its failures, a young woman living in the capitalist semi-periphery faced with terrible working conditions and the lack of any kind of opportunity. The public persona of Mimi Mercedez is largely dependent on different approaches towards and uses of negative stereotypes and roles – crime, prostitution, etc. – attempting to infuse them with positive meaning and give them a kind of legitimacy,

19 The original lyrics are: "Ja samo kažem nisam zadovoljna minimalnom platom. Oni zaključe da bavim se najstarijim zanatom". Or, in English: "I only say that I'm unhappy with minimum wage. They conclude that I'm working in the oldest trade".

not because they are by themselves positive, but because they represent a reality of living in contemporary Serbia, at least the way she, and many of her fans, see it.

One example of such a strategy is her frequent dealing with striptease and prostitution in the songs she writes, and later expanding on those topics in the interviews. She frequently emphasizes that she worked as a stripper, which is an experience she also describes in her songs (as in, for example, 'Bakšiš' ('Tips') and 'Parice, parice, pare' ('Money, money, money'). In an interview she gave in 2016, titled "Rap enabled me to not bust my ass as a stripper", she summed up the path she took from striptease to rap: "Neither love, nor hunger pushed me towards striptease, it was a rational calculation. I was sick of not having money to buy certain things I wanted, I thought long and hard about which job I could do without having connections, that paid more than 20.000 [a bit less than 200 euros today, at the time of the interview,it was considered the minimum wage], so I went to Mulin Rouge [a strip club in Belgrade] and asked about conditions of employment. I left it [striptease], because I don't want to work like a slave, and this is what rap enables me" (Ekspress.net 2016). A few aspects of the quote are especially important: the affirmation of a profession understood usually as morally problematic, with the emphasis that this was a *rational calculation*; the mention of the perpetual struggle of most people in Serbia and the Balkan region to obtain money and a further push towards affirming an opinion of younger generations which is often considered wrong or even dangerous by the older generations and (intellectual) elites – getting a lot of money with as little work as possible; finally, the importance of having connections in order to fulfill some basic needs, like getting adequate healthcare or finding a job.20 In Mimi's perspective, hence, one's achievements, or any form of success in life, are attributed mainly to personal skills and qualities, as any form of systemic support has been destroyed during the transition to neoliberalism, with individuals needing to develop what is commonly known as an entrepreneurial mindset in order to achieve any life goal.21 By putting striptease in focus in her songs and public appearances, she attempts to testify to the perceived reality of life in Serbia, and conditions in which young generations – mostly high school and university students – grew up and matured. Given that she speaks/raps about striptease as an empowering form of labor, ridiculing the men who spend a lot of money just to watch a (semi-)naked woman dance, she infuses it with meanings intended to be opposite to those adopted by the public, which would be inclined to take the moral high ground.

The song 'MMM' can be viewed as another manifest song, this time relating to a kind of "play" with labels – being a role model for some, and simultaneously a symbol of (moral) deterioration for others, a heroine and an antiheroine. The song begins with a statement, "times are hard, but I'm a tough woman", a woman who "sleeps all day and works all night", makes her own money so that she can live the way she wants.  Lyrics construct Mimi as

20 This final feature of the contemporary societies of the region is understood as an epigone of postsocialism by Čarna Brković (2017) in her book *Managing Ambiguity. How Clientelism, Citizenship, and Power Shape Personhood in Bosnia and Herzegovina*.

21 For more details on this mindset and its place within the music industry, see Ahl and Marlow 2021.

someone who uses the terrible living and working conditions to her advantage, because of an individual strength to persevere against the odds. In 'MMM', she also coined a kind of "chicken-or-egg" phrase that is often quoted in the media as well: "Is our country ruined because of people like me, or does a ruined country create people like me" ("Da l zbog takvih kao ja naša zemlja propada, ili zemlja propala stvara takve kao ja"). The line is often quoted in online interviews with Mimi (for instance: Vijesti 2018), and was even used by Nenad Čanak, a local politician to describe the lack of accountability for the devastation of contemporary Serbian society (LSV 2015).

### **Final Remarks**

The role of Mimi Mercedez as an antiheroine and a representative of a generation was carefully constructed throughout her career as a woman working within the male-dominated genre of hip hop/trap. As the genre and its surrounding culture offer ample strategies for formulating social criticism and speaking about different policies/politics and ideologies, she used a number of them – like the practice of dissing other rappers, or presenting sexually explicit content – to formulate a public figure that is loved by those who can relate to her music, but that can simultaneously be understood as a representative of a society in deep crisis, devastated by disaster capitalism. Through constructions of empowered femininity, understood primarily through an individualistic lens, the trapper built her leadership position by navigating the intricate matrixes of the music industry, expectations, failed expectations and labels. By addressing subjects like female sexuality and pleasure, striptease or making money quickly, she speaks to other members of her generation that grew up in a transitional society, offering them a kind of role model, but also a way to become empowered and successful as well. In that sense, the notion of leadership, understood often in a positive light, is deconstructed and used to construct a figure that represents opinions, attitudes and behaviors not necessarily desirable in a society. Employing both the figure of an empowered woman and of a role model, Mimi Mercedez in fact embodies a kind of antiheroine that also provokes critical thinking about concepts like empowerment and leadership.

#### Bibliography

### **Notes on Contributors**

**Nasim Ahmadian is** a Ph.D. candidate in Ethnomusicology at the University of Alberta, Canada. She received her M.A. (Ethnomusicology) and B.A. (Iranian Music Performance) from the University of Arts, Tehran, Iran. Her doctoral thesis focuses on the ethos of *hāl* and aesthetic education of sorrow in Iranian classical music. Her other research interests include identity and diaspora, academic decolonization, aesthetics and emotion, music education, and performing practice in Persian/Iranian classical music. Nasim is a professional *santūr* player and the founder of the internationally awarded Nasim Women's Ensemble based in Iran.

**Clementina Casula** is Assistant Professor in Sociology of Economic and Labor processes at the University of Cagliari, Italy. She holds a Diploma in Piano from the National Conservatory of Music of Cagliari and a Ph.D. in European Studies from the London School of Economics (U.K.). Her research – always paying a special attention to the gender dimension – has considered the role of institutional contexts in regulating different socioeconomic fields (such as territorial development, the information society, education-towork transitions, professionalization), with a focus on the field of cultural and creative industries (particularly music and audiovisual production).

**Ying-Hsien Chen** is currently a doctoral candidate in Musicology at the University of Helsinki. Her doctoral research concerns the transculturation of the Finnish folk instrument in global contexts, with special attention on Japanese women's interaction with, reinterpretation and resignification of the kantele.

**Linda Cimardi**is currently the Principal Investigator of the DFG-funded research project "Black Musics in the Region of (Former) Yugoslavia" based at the Martin Luther University in Halle-Wittenberg. She has been an Alexander von Humboldt Research Fellow at the former Phonogram Archive of the Ethnological Museum in Berlin (2018–2021), Guest Researcher in Ethnomusicology at the University of Music and Performing Arts in Graz (2017–2018) and research associate within the University of Turin Research Unit for the 2010–11 PRIN (Project of Relevant National Interest) in Ethnomusicology. Cimardi holds

a Ph.D. in Ethnomusicology from the University of Bologna (2013). She conducted fieldwork in Italy,Uganda,Croatia, Bosnia and Austria.Her main areas of interest are African musics and dances, gender in performing arts, politics and aesthetics of world music.

**Bahar Gjuka** is currently a Ph.D. candidate in Musicology at the University of Calgary. She completed her bachelor degree in Turkey,majoring in Traditional Turkish Music and vocal, *kaval* and classical *kemençe* (*klasik kemençe*) performance. Her M.A. thesis focused on Turkish folk music in Macedonia. Throughout her academic career, she has worked as a music teacher and a teaching assistant. Bahar has been awarded many scholarships, including the Alberta Graduate Excellence Scholarship and the Canadian Muslims for Peace and Justice (CMPJ) award. She has performed in the Canadian province of Alberta (Calgary and Edmonton) and Georgia, US, as part of TurCan Musicians, World Music Ensemble, Sofra Ensemble, Musiki Flow music ensembles, and presented papers/lecture recitals at international scholarly conferences.

**Laura Hamer** is a Senior Lecturer in Music and Associate Director of Student Support (Arts and Humanities) at The Open University. Her research specialism lies in Women in Music. Her books include *Female Composers, Conductors, Performers: Musiciennes of Interwar France, 1919–1939* (Routledge, 2018) and *The Cambridge Companion to Women in Music since 1900* (ed. Cambridge University Press, 2021). She is currently co-editing, with Helen Julia Minors, *The Routledge Companion to Women's Musical Leadership: The Nineteenth Century and Beyond* and PI of the AHRC-funded Women's Musical Leadership Online Network.

**Diane Kolin** is a Ph.D. student in Musicology in York University, Toronto, Canada. Her research interests are diverse and include Critical Disability Studies, Ludwig van Beethoven, and Franz Liszt. She is the editor in chief of *The Journal of the French Beethoven Society – Association Beethoven France et Francophonie*.The study of Beethoven's deafness and her personal history led to her research in disability and music. Her collaboration with disabled musicians in the professional musical world allows her to expose new ideas on making music more accessible to a broader audience.

**Blanche Lacoste** completed her Ph.D. in Ethnomusicology (Aix-Marseille University – Tor Vergata University – École Française de Rome) in 2021. She is currently teaching adjunct in Ethnomusicology at the Jean Monnet University, in Saint-Étienne. Her Ph.D. research focused on the musical role of women in the Christian services of migrant communities in Rome. Her research interests lie on the boundary between gender studies, ethnomusicology, migration studies and religious studies.

**Helen Julia Minors** is Professor and Head of the School of Arts at York St John University. She was previously School Head of Performing Arts and Associate Professor of Music at Kingston University London. She is founder and co-chair of EDI Music Studies Network. Recent publications include: *Artistic Research in Performance Through Collaboration*, edited with Martin Blain (Palgrave 2020) and *PaulDukas: Legacies of a FrenchMusician*, co-edited with Laura Watson (Routledge, 2019), as well as chapters in *Opera and Translation* (John Benjamins, 2020), and articles in *Tibon* (2021), *London Review of Education* (2019, 2017) and entries in the *Cambridge Stravinsky Encyclopedia* (2021). She is currently co-editing, with Laura Hamer, *The Routledge Companion to Women's Musical Leadership: The Nineteenth Century and Beyond* and is CI of the AHRC-funded Women's Musical Leadership Online Network with Laura Hamer.

**Katarina Mitić Minić** is a Ph.D. candidate at the Theory of Arts and Media Department (Interdisciplinary Studies) of the University of Arts in Belgrade. She finished bachelor and master studies at the Department of Musicology, Faculty of Music in Belgrade. The focus of her research work is the question of the relationship between music and movies, series and video games, music industry and music in marketing. She worked for Warner Music Group music company and 20h Century Fox film studio. Currently, Katarina is engaged as production manager of Girls Rock Camp in Serbia and is part of YoungWomen's Collective FEMIX.

**Iva Nenić** is an ethnomusicologist and cultural theorist who works as an assistant professor at the Department of Ethnomusicology, Faculty of Music, of the University of Arts in Belgrade. Iva's research is concerned with the way music and wider cultural practices give rise to ideology and help enact social identities, with a focus on gender reproduction/contestation and the politics of intersectionality, as well as on the relationship between sustainability and transhumanist aspects of contemporary culture. She collaborates with the postgraduate program of Interdisciplinary studies at the University of Arts in Belgrade; Belgrade Open School; Women's Studies Center in Belgrade; as well as other Serbian and international academic institutions. Her invited lectures took place at universities in UK, Austria, Slovenia, Italy, and Japan. Iva's field experience spans from the folk music of Serbia to the issues of local and global world music; female musicianship in Serbian and regional independent music scenes; Balkan-based hip hop, and shared vernacular culture of post-Yugoslav pop-folk. Her book *Gusle Players and Other Female Traditional Instrumentalists in Serbia: Identification by Sound* (Clio, Belgrade, 2019) received Anđelka Milić Award granted by the Section for Feminist Research and Critical Studies on Masculinities (SEFEM), in the category of scholarly work critically contributing to the study of gender relations. She is the leader of the scientific research project "Female Leadership in Music" (FLIM), supported by the Science Fund of Serbia (PROMIS program).

**Tatjana Nikolić** is a Research Assistant at the Faculty of Dramatic Arts (FDA), University of Arts in Belgrade and a member of the team of "Female leadership in music" project supported by the Science Fund of the Republic of Serbia, no. 6066876, 2020 – 2022. Since 2010 she has been a member of a Young Women's Collective FEMIX, where she is researching, advocating, promoting, educating, and organizing events to enhance the participation of young womenin the local cultural and creative scene. In 2016 her study "Gender Relations within the Alternative Music Scene of Serbia and the Balkans" was awarded and published by the Provincial Institute for Gender Equality of Vojvodina.Currently, she is a Ph.D. candidate at the FDA with the doctoral thesis titled "Gender and Age Equality in the Cultural Policy of Serbia".

**Bojana Radovanović**, musicologist and art theorist, is a Research Assistant at the Institute of Musicology, Serbian Academy of Sciences and Arts in Belgrade. She obtained her Ph.D. at the Department of Musicology, Faculty of Music, University of Arts in Belgrade, studying the relations of voice with vocal technique and new technologies in contemporary art and popular music. Her research interests include contemporary music and art, voice,metal music, art and media, and transdisciplinary research. She has published two books and co-edited one collective monograph. She is one of the founders of the Association for preservation, research and promotion of music "Serbian Composers" that works on the largest internet audio-visual archive of Serbian art and film music, and a co-founder and the editor-in-chief of the scientific journal*INSAM Journal of Contemporary Music, Art and Technology*.

**SanjaRanković** is Associate Professor of Traditional singing at the Department of Ethnomusicology, Faculty of Music, of the University of Arts in Belgrade. Her ethnomusicological interests are in the field of applied ethnomusicology as well as in vocal practices. She has delivered numerous lectures, seminars, concerts and workshops in Serbia, as well as abroad. For almost two decades, she has been working as a lecturer in traditional singing at the Serbian Folk Dance and Song Study Centre of the National Ensemble "Kolo". She is the author of three books and two full-length musical stage plays, which were performed at the National Theatre in Belgrade.

**Adriana Sabo** is a Ph.D. candidate at the Postgraduate School ZRC SAZU in Ljubljana, Slovenia. She was a Ph.D. candidate at the Department of Musicology, Faculty of Music, of the University of Arts in Belgrade (2013–2020), and was employed as a Junior Researcher and a Research Assistant at the same institution. She holds master degrees in musicology (2012) and gender studies (2015). She was a recipient of the scholarship given by theMinistry of Education, Science and Cultural Development of the Republic of Serbia (2014–2018). She is a member of the Serbian Musicological Society, International Association for the Study of Popular Music (IASPM, international branch) and a contributor for the Center for Popular Music Research (Belgrade).

**Carol Silverman,** Professor Emerita of Cultural Anthropology and Folklore/Public Culture at the University of Oregon, has done research with Roma for over 40 years in the Balkans, Western Europe and the US, on politics, music, human rights, gender, and migration, with a focus on representation. Her 2012 book *Romani Routes: Cultural Politics and Balkan Music in Diaspora* (Oxford), won the book prize from the Society for Ethnomusicology, and her 2021 book *Ivo Papazov's Balkanology* (Bloomsbury) analyzes the politics of Bulgarian wedding music. She has published recent articles in the edited volumes *The Oxford Handbook of Economic Ethnomusicology*, *The Roma and their Struggle for Identity in Contemporary Europe*, and *The Romani Women's Movement: Struggles and Debates in Central and Eastern Europe*, and the journals *Critical Romani Studies*, *Western Folklore*, and *Ethnomusicology Forum*. She works with the USNGO Voice of Roma, is curator for Balkan music for the digital RomArchive, and is a professional vocalist and teacher of Balkan music.

**TaliehWartner-Attarzadeh** is a doctoral candidate in Ethnomusicology at the University of Music and Performing Arts in Graz, Austria. In her doctoral project, she investigates post-revolutionary Iranian puppets and how they resist government-based restrictions against music and dance on Iranian national television. Previously, she has researched Islamic women's rituals from southern Iran, about which she wrote her BA and MA theses. Her research interests include music cultures from West Asia and Islamic countries. Moreover, she is interested in issues considering media, political, religious, and gender aspects within the ethnomusicological framework.

**Mirjana Zakić** is Professor of Ethnomusicology at the University of Arts in Belgrade. She graduated at the Department of Ethnomusicology, Faculty of Music in Belgrade, where she defended herM.A. thesis: "Instrumental and vocal-instrumental heritage of Zaplanje region in the light of traditional music opinion", as well as her doctoral dissertation "Ceremonial songs of winter season- systems of music signs in the tradition of the southeastern Serbia". Since 1990 she has been employed at the Faculty of Music at the University of Arts in Belgrade. She was the Vice-Dean at the Faculty of Music in Belgrade (2012–2015). Since 2018 she has been the Head of the Department of Ethnomusicology at the Faculty of Music. So far, she has published four books and a large number of papers in national and international publications. She is especially interested in ritual music, instrumental music, musical semiotics, relation between text and context. She is currently the chairman of the Serbian Society of Ethnomusicology.

# Cultural Studies

Gabriele Klein Pina Bausch's Dance Theater Company, Artistic Practices and Reception

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 Markus Gabriel, Christoph Horn, Anna Katsman, Wilhelm Krull, Anna Luisa Lippold, Corine Pelluchon, Ingo Venzke Towards a New Enlightenment – The Case for Future-Oriented Humanities

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*2.1.3 Different types of PV cell*

Typically, there are four primary kinds of solar cells, which include the following: (1) Monocrystalline solar cells, (2) polycrystalline cells (multi-silicon cells), (3) amorphous solar cells, and (4) thin film solar cells.

(1) *Monocrystalline solar cells*, which are also known as single crystalline cells (**Figure 1**), can be differentiated from other types of solar cells by their dark black appearance. As a result of this look, monocrystalline solar cells are easily identifiable in comparison to other forms of solar cells. They are made using an incredibly pure type of silicon, which is what has driven them to the position of being the most effective material for the process of converting sunlight into electricity. As a result of this, solar panels have risen to the position of being the most effective material. Solar photovoltaic cells made from monocrystalline silicon have an efficiency of 15%\*, making them the most effective but also the most expensive option. They are capable of producing up to four times as much electricity as

**Figure 4.** *Polycrystalline.*

thin-film solar panels, but they only take up a small fraction of the space. In environments with low light, their performance is superior to that of other panels, and they have a longer lifespan. The most major downside of this option, as well as the primary reason why it does not enjoy more popularity among homeowners, is the high cost. In addition, dust and shadows can cause the circuit to malfunction, and the method of manufacturing that involves cutting the cells into wafers is usually regarded as being inefficient.

(2) At the very beginning of the 1980s, the solar industry developed polycrystalline cells (**Figure 4**), which are also known as *multi-silicon cells*. These cells were the very first solar cells ever made for use in commercial applications. Inside the cell, the process of synthesis can result in the formation of a number of crystalline formations. It is less difficult to put into action in a production line. It is far less expensive than monocrystalline, despite the fact that it is less effective.

(3) *Amorphous solar cells*, which are neither organised nor crystallised at the molecular level (**Figure 5**), were traditionally used for smaller-scale applications because the term "amorphous," which means "shapeless" in English, gives the impression that they are.

(4) *Thin film Solar cells—*During the manufacturing process, several layers of photovoltaic material are layered on top of one another and stacked in the form of modules that are constructed of thin film solar cells. Using this process to develop a cell (thin film) results in a lesser requirement for silicon, which in turn results in cheaper production costs. In most cases, it is less expensive, but the rate of efficiency it achieves is significantly lower [7].


**About the Editors**

### **Hiten D. Mistry**

Dr. Hiten Mistry is the Senior Research Fellow, Department of Women and Children's Health, School of Life Course and Population Health Sciences, King's College London, working on a range of global women's health studies. Dr. Mistry received a first-class BSc (Hons) in biochemistry with industrial experience from the University of Manchester Institution of Science and Technology (UMIST). He trained as a PhD scientist in Professor Fiona Broughton Pipkin's lab, University of Nottingham, followed by 6 years as a Postdoctoral Research Associate with Professor Lucilla Poston at King's College London and Personal Fellowships at the Universities of Bern (European Renal Association-European Dialysis and Transplantation Association Long-term Fellowship) and Nottingham (British Heart Foundation, Intermediate Basic Science Research Fellowship). Dr. Mistry's main research interests are the pathophysiology of the hypertensive diseases of pregnancy and nutrition in pregnancy. He has published widely in the field, including peer-reviewed journals, expert reviews, book chapters, Guest Editor for Special Issues, and conference proceedings. He is also on the Editorial board for *Placenta*; Associate Editor for *Frontiers in Cardiovascular and Smooth Muscle Pharmacology*; Review Editor for *Frontiers in Reproduction*, *Frontiers in Developmental Endocrinology* and *Frontiers in Integrative Physiology*; and Topical Advisory Panel Member for *IJMS*.

### **Eun Lee**

Dr. Eun Lee is the Assistant Professor, Department of Microbiology and Immunology, School of Medicine, Virginia Commonwealth University, Richmond, Virginia, USA. Her laboratory's research interest is in immunological contributions to the development of pre-eclampsia, fetal growth restriction, and repeated spontaneous miscarriage, focusing on placenta development during early pregnancy. Dr. Lee received her PhD from the University of Cincinnati and special research associate training at Harvard University, followed by additional training as a Research Postdoctoral Fellow at Emory University, Department of Transplant Surgery. She has published widely in the field, including peer-reviewed journals and expert reviews, and has served as Guest Editor for Special Issues and conference proceedings. She is also on the editorial board for *Frontiers in Cellular Biology*.

## *Editorial* **Placental Related Disorders of Pregnancy**

**Eun D. Lee 1 and Hiten D. Mistry 2,\***

We are pleased to present this Special Issue of *International Journal of Molecular Sciences*, entitled 'Placental Related Disorders of Pregnancy'. The placenta is a unique organ, produced outside the embryo and connected by a cord of vessels, and is formed as a result of various degrees of interactions between fetal and maternal tissues within the pregnant uterus. The placenta fulfils a variety of functions, which are completed by several different organs in adult life. Unlike the relatively stable mature adult organs, the placenta is programmed to complete very different functions during development. Thus, the placenta can be described as a constantly evolving organ. Its major role is the homeostasis of a protected environment for the undisturbed growth and development of an embryo/fetus.

Placental-related disorders of pregnancy are almost unique to the human species and affect around a third of human pregnancies. Many of these disorders result in increased maternal and fetal mortality and morbidity and can have life-long health implications for both the mother and her child. Recent changes in human lifestyle, such as delayed childbirth and hypercaloric diets, may have increased the global incidence of placentalrelated disorders over recent decades.

This Special Issue is a compilation of 21 research manuscripts and reviews, covering all aspects of placentation, with a particular focus on those related to placental function and disorders of pregnancy. The manuscripts cover aspects of placental physiology, biochemistry and molecular biology, and clinical and animal models are also included in this excellent Special Issue.

This collection contains some excellent reviews. The first review covers the homeostasis of the cytokine interleukin-15 (IL-15) in healthy pregnancy, providing up-to-date mechanisms of the action of IL-15 at the maternal–fetal interface [1]. A fascinating review by Anthony Carter covers why human placentation is so unique, with in-depth details on placentation in different animals to wonderfully illustrate this [2]. This is followed by a comprehensive review covering the important condition of gestational diabetes and the contribution of the placenta in the associated immunoendocrine dysregulation [3]. Finally, a very topical and informative overview highlighting the role of the placenta and the use of low-dose aspirin in the prevention of pre-eclampsia [4,5]. In addition to the reviews, our collection also contains several novel studies covering pre-eclampsia [6–8]; fetal growth restriction [7,9–11]; calcium signaling [12]; placental oxidative stress, nutrition, senescence and apoptosis [6,9,13–15]; sexual dimorphism [16–18], intrahepatic cholestasis [19]; placental vascular modelling [20]; and placental villous explant culture models [21].

This Special Issue presents placental research using a range of established and stateof-the-art techniques showcasing novel and up-to-date data to enhance and facilitate our understanding of placentation as well as mechanisms that result in associated adverse pregnancy outcomes, as well as longer-term risks of complications.

**Funding:** This research received no external funding.

**Conflicts of Interest:** The authors declare no conflict of interest.

**Citation:** Lee, E.D.; Mistry, H.D. Placental Related Disorders of Pregnancy. *Int. J. Mol. Sci.* **2022**, *23*, 3519. https://doi.org/10.3390/ ijms23073519

Received: 14 March 2022 Accepted: 22 March 2022 Published: 24 March 2022

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

**Copyright:** © 2022 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/).

### **References**


**2. Overview of various blast cells**

#### **2.1. Erythroblasts**

In H&E-stained samples, it is difficult to distinguish between erythroblasts, myeloblasts, and megakaryoblasts. Erythroblasts have a large nucleus that occupies the whole cell. In H&Estained sections, the nucleus is observed to be pale, basophilic, and homogenous, with a fine appearance. Myeloblast lineages have more eosinophilic and rough cytoplasm than the erythroblasts, with distinct nucleoli (**Figure 1A** and **B**). Megakaryoblasts have transparent, lobulated nucleoli, with a higher nuclear-cytoplasmic ratio than that in megakaryocytes. The cytoplasmic border is frequently observed, and cell membranous projections are occasionally observed in some of the megakaryoblasts (**Figure 1C**).

#### **2.2. Immature myelocytic lineage**

In general, the morphological characteristics of myelocytic developmental stages have not been sufficiently described using H&E-stained clot samples. This is probably because of the difficulty in recognizing the cytoplasmic granules in the H&E-stained sections. However, H&E-stained sections provide incomplete morphological information regarding the developmental stages. In comparison with erythroblasts, myelocytic lineages are larger and have eosinophilic cytoplasm. Pro-myelocytes are smaller than myeloblasts and have a halo surrounding the nucleus, which is sometimes observed in M-G–stained samples (**Figure 2A**). Myelocytes and meta-myelocytes are easily identifiable owing to their segmented nuclei and smaller size than that of myelocytes (**Figure 2B** and **C**). Eosinophilic and basophilic lineages are identifiable because of the presence of distinct granules (**Figure 2D**).

To assist in morphologic diagnosis, immunohistochemistry (IHC) is available for assessment and immunophenotyping. For instance, by IHC, the marker glycophorin can assess the myeloid-erythroid cell ratio, and spectrin can efficiently detect erythroid cellular lineage [9]. P53 can also be used for differential diagnosis between refractory anemia and aplastic anemia [10]. An international Working Party for the Standardization of Bone Marrow IHC was formed by the International Council for Standardization in Hematology to prepare a set of guidelines for the standardization of handling BM specimens and reports [11]. While the histological examination of BM introduces new aspects of blood disease, the diagnosis of hematopoietic disorders using H&E-stained BM clot sections remains a challenge for nonhematopathologists. In fact, hematopoietic disorders have been diagnosed using May-Grünwald Giemsa (M-G) staining by hematologists and pathologists, and the findings obtained from H&E-stained BM

clot sections are used as a reference for those obtained from M-G–stained samples.

cytic proliferative neoplasm (MDS/MPN).

**2. Overview of various blast cells**

observed in some of the megakaryoblasts (**Figure 1C**).

**2.2. Immature myelocytic lineage**

**2.1. Erythroblasts**

10 Myeloid Leukemia

This review discusses the information obtained from H&E-stained BM clot sections and its advantages and limitations over M-G–stained BM clot sections. The techniques are discussed with respect to examination of erythrocytes and myelocytes and the diagnosis of acute myeloid leukemia (AML), myelodysplastic syndrome (MDS), and myelodysplastic syndrome/myelo-

In H&E-stained samples, it is difficult to distinguish between erythroblasts, myeloblasts, and megakaryoblasts. Erythroblasts have a large nucleus that occupies the whole cell. In H&Estained sections, the nucleus is observed to be pale, basophilic, and homogenous, with a fine appearance. Myeloblast lineages have more eosinophilic and rough cytoplasm than the erythroblasts, with distinct nucleoli (**Figure 1A** and **B**). Megakaryoblasts have transparent, lobulated nucleoli, with a higher nuclear-cytoplasmic ratio than that in megakaryocytes. The cytoplasmic border is frequently observed, and cell membranous projections are occasionally

In general, the morphological characteristics of myelocytic developmental stages have not been sufficiently described using H&E-stained clot samples. This is probably because of the difficulty in recognizing the cytoplasmic granules in the H&E-stained sections. However, H&E-stained sections provide incomplete morphological information regarding the developmental stages. In comparison with erythroblasts, myelocytic lineages are larger and have eosinophilic cytoplasm. Pro-myelocytes are smaller than myeloblasts and have a halo surrounding the nucleus, which is sometimes observed in M-G–stained samples (**Figure 2A**). Myelocytes and meta-myelocytes are easily identifiable owing to their segmented nuclei and smaller size than that of myelocytes (**Figure 2B** and **C**). Eosinophilic and basophilic lineages

are identifiable because of the presence of distinct granules (**Figure 2D**).

**Figure 1.** Morphology of erythroblasts and myeloblasts. (A) an erythroblast showing a transparent nucleus with condensed nucleoli (600×). (B) a myeloblast showing a transparent nucleus with one prominent eosinophilic nucleolus. The cytoplasm is eosinophilic, rough, and heterogeneously condensed (600×). (C) Two megakaryoblasts show transparent and lobulated nuclei with prominent eosinophilic nucleoli. The cytoplasm is eosinophilic, rough, and heterogeneously condensed. The edges are irregular, with a number of villi (600×).

**Figure 2.** Morphology of myelocyte lineages detected by H&E staining. Immature neutrophil lineages (A–C) and immature eosinophil lineages (D). (A) A pro-myelocyte showing a nucleus surrounded by halo (represented by an arrow). Nucleoli are not prominent relative to myeloblasts. The cytoplasm is eosinophilic, rough, and heterogeneously condensed (600×). (B) A myelocyte showing a regular oval nucleus with a contour and without indentation. The cytoplasm is eosinophilic, rough, and heterogeneously condensed (600×). (C) A meta-myelocyte showing a U-shaped or bent nucleus. The cytoplasm is eosinophilic, rough, and heterogeneously condensed. No nucleoli are visible (600×). (D) Variable immature eosinophil lineages. The arrow indicates a pro-myelocyte, and the arrowhead indicates a myelocyte. A mature eosinophil can be seen in the upper-left corner (600×).