**1. Introduction**

This chapter provides a contextual background to those that follow by describing the GFC and its salient characteristics, and identifying salient causes of the crisis. Once these salient causes have been identified, the thesis proceeds to investigate the extent of the role, if any, that economics and political mechanisms underlying securitization may have had in facilitating the GFC. Financial economists generally trace the beginnings of the GFC to approximately mid-2007, when a number of key mortgage lenders specialising in sub-prime housing loans experienced financial distress. For a number of reasons, banks and other mortgage originators had, in the years preceding the GFC, been able to lend home loans to lowto-mid-income borrowers1 This practice, and the securitization arrangements based on it, would generally not have proved problematic if house prices throughout the United States had continued to appreciate as they had under speculative boom conditions. Problems arose, however, when the U.S. housing boom burst in 2006, and particularly in residential areas housing concentrations of 'sub-prime' borrowers.

1 Often referred as subprime borrowers who, under normal lending criteria, would have been refused loans (eg. because of poor credit histories).

As investors became increasingly reluctant to invest in securities based on subprime housing mortgages, this financial distress spread to securitizers of a subprime mortgage loans, and was further exacerbated when credit rating agencies such as Standard & Poor's, Moody's, and Fitch downgraded many mortgage-backed securities. In the words of Allen and Carletti, the mortgage-backed sub-prime home loan securitization market 'simply broke down' [1] and a general loss of confidence became more widespread, affecting commercial asset-backed securitization markets in the latter half of 2007. Banks sponsoring many residential and commercial securitizers were required, under the terms of cross-guarantee arrangements, to pay debts that otherwise would have remained off-balance-sheet as contingent liabilities [2].

their traditional roles; speculative asset bubbles; and the U.S. sub-prime crisis and

This chapter looks into the main causes of the crisis, while developing a discussion on the contribution of each individual factor for the onset of the financial crisis. The chapter finds that GFC 2007 is a result of a number of factors. Some factors are linked with political decisions dated decades back in U.S political agenda, while some factors are market driven. The structure of the chapter is as fallows. Section 2 is a brief discussion on history of financial crisis in the modern world. Section 3, the main section of the chapter is a discussion on GFC 2007, with a special emphasis on housing bubble. This section glances over a number of contributory factors to the GFC including inter alia economical, financial, legal and behavioural factors that

Although examples of speculative bubbles are recorded in ancient times, in more recent times the most commonly cited early example of a speculative asset bubble is the Tulip Bubble in the 1600s. Tulips imported from East to Holland in the 1600s became a collector's item, and tulip bulbs were sold as very high prices. An influx of speculative funds was accompanied by a surge in financial innovation until the bubble burst in 1673, and many who had purchased bulbs on credit went bankrupt,

A second commonly cited speculative bubble in early modern financial history was the collapse of the South Sea Company, reported in England in 1720. The South Sea Company was a joint stock company, which was awarded a Royal Charter (monopoly rights) to trade in North and South America, and became the subject of massive speculation throughout Europe. The company's share price, recorded at £128 in January 1720, increased almost tenfold to £1000 over the next 6 months to July 1720. By the end of 1720 following a bursting of the bubble, however, it had

It was in early 1920s that the Florida real estate bubble burst. However the ability to purchase real estate with a down payment of 10% provided the leverage to the asset bubble. Accordingly house prices went up grabbing more peculators in to the business. The bubble burst in advance with a typhoon hitting Florida causing massive property damage. The sudden drop in prices paved the way for bankruptcies and default. The Great depression, the most longest, widespread, and deepest depression of the 20th century took place after the stock market crash of October 29, 1929. The speculative asset bubble started to grow in late 1920s' with the boom in many industries3 resulting stock market speculation and paving way for thousands of investors to invest in the stock market, were as most of the investors have borrowed the money for investments. The asset bubble rose to such a high extent that the lenders have given loans up to three times of the face value of the stocks investors have purchased. Expecting stock prices to raise more, more and more funds were invested in the stock market creating a massive asset bubble by 1929. At the end with the dropping commodity prices the stock prices began to fall. By October 29, panic selling started and the stock market collapsed, leading to the

The 'Tronics' burst took place in 1961 with emergence of electronics in the market. A number of investors were keen on investing shares belonging to

the fallout resulting from it [6, 7].

*DOI: http://dx.doi.org/10.5772/intechopen.90728*

reverted to £124 per share [10].

longest depression in the world history [11–14].

3 Steel production, building, automobiles etc.

**59**

may have contributed to the onset of the crisis.

*Political and Institutional Dynamics of the Global Financial Crisis*

**2. Speculative asset bubbles in modern financial history**

precipitating an economic depression all over the country [8, 9].

Institutional and corporate investors internationally had also purchased securitization products, adding to the linkages between large financial institutions in different jurisdictions. At about the same time, other banks in the United States, Britain and elsewhere in Europe—themselves uncertain about the extent to which they might be called to make unexpectedly large payments from their reserves under their own cross-guarantee arrangements with related securitizers and other companies—became reluctant to provide any more than very short term liquidity (of more than a few days' tenor) to each other. Institutional investors engaged in a 'flight to quality', investing in highly liquid, secure assets such as Treasury bills and other government securities. In approximately March 2008, company reports of further bad debts and asset write-downs because of mark-to-market accounting increased uncertainty about counterparty risk levels, with the result that global investment bank Bear Stearns Companies Inc. was unable to secure wholesale funding to continue its operations past mid-March, when it was sold to JP Morgan Chase & Co. for approximately 7% of its pre-crisis equity value [3].

Internationally, central banks in consultation with their governments intervened in their respective economies by markedly reducing official or cash rates; injecting liquidity into the system by effectively lending to primary dealers (e.g. by allowing them to swap less liquid asset-backed securities for Treasury securities, often at a substantial discount); and so-called government 'bailouts' of securitizing institutions perceived to be economically significant or 'too big to fail' (such as Northern Rock in Britain; and Bear Stearns, Fannie Mae and Freddie Mac in the U.S.) [4, 5].2 In subsequent months, real economies in the United States, Britain and elsewhere in Europe have exhibited historically poor performance, with relatively high unemployment and low economic growth, despite relatively low interest rates and inflation.

Abstracting somewhat from this background, the GFC's chief characteristics as identified in the literature can be clustered around excessive system liquidity; high levels of executive compensation by community standards; high levels of financial innovation; banks and other financial intermediaries undertaking activities beyond

2 A number of high-profile investment bank securitizers requested government support, including Bear Stearns, Merrill Lynch, Wachovia, Goldman Sachs, and Morgan Stanley. Of these, Bear Stearns, Merrill Lynch and Wachovia were ultimately sold at well below their year high equity prices, while Goldman Sachs and Morgan Stanley ultimately became commercial bank holding companies, subject to prudential regulation but able to access Federal Reserve swaps into liquid assets at substantially discounted prices. Another high-profile securitizer, Lehman Brothers, went into involuntary liquidation. American International Group (AIG), a global insurer and sub-insurer which had ultimately insured many of the securitization schemes affected by collapsing asset prices, was saved from liquidation by a U.S. Federal Reserve Bank 'rescue package' that enabled AIG to deliver additional collateral to its credit default swap trading partners

### *Political and Institutional Dynamics of the Global Financial Crisis DOI: http://dx.doi.org/10.5772/intechopen.90728*

As investors became increasingly reluctant to invest in securities based on subprime housing mortgages, this financial distress spread to securitizers of a subprime mortgage loans, and was further exacerbated when credit rating agencies such as Standard & Poor's, Moody's, and Fitch downgraded many mortgage-backed securities. In the words of Allen and Carletti, the mortgage-backed sub-prime home loan securitization market 'simply broke down' [1] and a general loss of confidence became more widespread, affecting commercial asset-backed securitization markets in the latter half of 2007. Banks sponsoring many residential and commercial securitizers were required, under the terms of cross-guarantee arrangements, to pay debts that otherwise would have remained off-balance-sheet as contingent

Institutional and corporate investors internationally had also purchased securitization products, adding to the linkages between large financial institutions in different jurisdictions. At about the same time, other banks in the United States, Britain and elsewhere in Europe—themselves uncertain about the extent to which they might be called to make unexpectedly large payments from their reserves under their own cross-guarantee arrangements with related securitizers and other companies—became reluctant to provide any more than very short term liquidity (of more than a few days' tenor) to each other. Institutional investors engaged in a 'flight to quality', investing in highly liquid, secure assets such as Treasury bills and other government securities. In approximately March 2008, company reports of further bad debts and asset write-downs because of mark-to-market accounting increased uncertainty about counterparty risk levels, with the result that global investment bank Bear Stearns Companies Inc. was unable to secure wholesale funding to continue its operations past mid-March, when it was sold to JP Morgan

Internationally, central banks in consultation with their governments intervened in their respective economies by markedly reducing official or cash rates; injecting liquidity into the system by effectively lending to primary dealers (e.g. by allowing them to swap less liquid asset-backed securities for Treasury securities, often at a substantial discount); and so-called government 'bailouts' of securitizing institutions perceived to be economically significant or 'too big to fail' (such as Northern Rock in Britain; and Bear Stearns, Fannie Mae and Freddie Mac in the U.S.) [4, 5].2 In subsequent months, real economies in the United States, Britain and elsewhere in Europe have exhibited historically poor performance, with relatively high unemployment and low economic growth, despite relatively low interest rates and

Abstracting somewhat from this background, the GFC's chief characteristics as identified in the literature can be clustered around excessive system liquidity; high levels of executive compensation by community standards; high levels of financial innovation; banks and other financial intermediaries undertaking activities beyond

2 A number of high-profile investment bank securitizers requested government support, including Bear Stearns, Merrill Lynch, Wachovia, Goldman Sachs, and Morgan Stanley. Of these, Bear Stearns, Merrill Lynch and Wachovia were ultimately sold at well below their year high equity prices, while Goldman Sachs and Morgan Stanley ultimately became commercial bank holding companies, subject to prudential regulation but able to access Federal Reserve swaps into liquid assets at substantially discounted prices. Another high-profile securitizer, Lehman Brothers, went into involuntary liquidation. American International Group (AIG), a global insurer and sub-insurer which had ultimately insured many of the securitization schemes affected by collapsing asset prices, was saved from liquidation by a U.S. Federal Reserve Bank 'rescue package' that enabled AIG to deliver additional collateral to its credit default swap

Chase & Co. for approximately 7% of its pre-crisis equity value [3].

liabilities [2].

*Financial Crises - A Selection of Readings*

inflation.

trading partners

**58**

their traditional roles; speculative asset bubbles; and the U.S. sub-prime crisis and the fallout resulting from it [6, 7].

This chapter looks into the main causes of the crisis, while developing a discussion on the contribution of each individual factor for the onset of the financial crisis. The chapter finds that GFC 2007 is a result of a number of factors. Some factors are linked with political decisions dated decades back in U.S political agenda, while some factors are market driven. The structure of the chapter is as fallows. Section 2 is a brief discussion on history of financial crisis in the modern world. Section 3, the main section of the chapter is a discussion on GFC 2007, with a special emphasis on housing bubble. This section glances over a number of contributory factors to the GFC including inter alia economical, financial, legal and behavioural factors that may have contributed to the onset of the crisis.


**Author details**

Simon Ogbeche Odey1 \* and Raphael Segun Bello2

1 Department of Wood Products Engineering, Cross River University of Technology, Calabar, Nigeria

2 Department of Agricultural and Bio-Environmental Engineering, Federal College of Agriculture, Ebonyi State, Nigeria

\*Address all correspondence to<EMAIL_ADDRESS>
© 2023 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.

*Modeling Growth and Yield of Crops Using Different Tillage Systems DOI: http://dx.doi.org/10.5772/intechopen.113410*


*3.7. Splitting Tensile Strength*

The average results of three 100 mm × 200 mm cylinders that tested for splitting tensile strength are shown in Table 7. The tensile strength of HPSCC was 1.53 times that for NSVC, while HSSCC had a tensile strength of only 14% higher than NSVC, remembering that its compressive strength was 67% higher. When comparing the ratio of tensile strength divided by the square root of compressive strength, NSVC had a value of 0.62, but a higher value of 0.65 was recorded for HPSCC mix, 0.66 for HPVC, and again HSSCC was lower and it was only 0.55. Piekarczyk recorded a ratio of 0.61 for an NSC and 0.65 for an SCC [1]. Others stated that the relationship between tensile and compressive strength of SCC is similar to that of VC [2]. Research showed that the average direct tensile strength of the SCC was found to be 3.5 MPa, whilst the average splitting tensile strength was found to be 3.8 MPa, which is only 8.6% higher [58].

**Table 7.** Splitting tensile strength of Ø100 mm specimens, Flexural strength of 75 mm × 75 mm × 350 mm concrete prisms, and Modulus of Elasticity of Ø150 mm specimens.

### *3.8. Flexural Strength*

The average test results of three 75 mm × 75 mm × 350 mm prisms at age of 90 days were presented in Table 7. HPSCC developed a flexural strength 15% lower than that of HPVC, while it was about 50% higher than both HSSCC and NSVC. The ratio was 0.75 in the case of HPSCC; it was 0.68 for an NSVC and 0.78 for an HPVC. When comparing the results of splitting tensile strength and the flexural strength, it can be noted that the concrete prisms with the higher strength behaved better against tensile stresses than the splitting cylinders.


**Pelvic Movement in Aging Individuals and Stroke Patients** Provisional chapter Pelvic Movement in Aging Individuals and Stroke

Hitoshi Asai

Patients

[48] Holmes JD, Jenkins ME, Johnson AM, et al. Validity of the Nintendo Wii® balance board for the assessment of standing balance in Parkinson's disease. Clin Rehabil. 2013;**27**(4):

[49] Capicíková N, Rocchi L, Hlavacka F, et al. Human postural response to lower leg muscle

[50] Barbieri G, Gissot AS, Fouque F, et al. Does proprioception contribute to the sense of

[51] Thompson C, Bélanger M, Fung J. Effects of bilateral Achilles tendon vibration on pos‐ tural orientation and balance during standing. Clin Neurophysiol. 2007;**118**(11):2456–67.

[52] Ivanenko YP, Solopova IA, Levik YS. The direction of postural instability affects postural reactions to ankle muscle vibration in humans. Neurosci Lett. 2000;**292**(2):103–6.

[53] Ceyte H, Cian C, Zory R, et al. Effect of Achilles tendon vibration on postural orienta‐

[54] Brumagne S, Janssens L, Janssens E, et al. Altered postural control in anticipation of pos‐ tural instability in persons with recurrent low back pain. Gait Posture. 2008;**28**(4):657–62.

[55] Janssens L, Brumagne S, Polspoel K, et al. The effect of inspiratory muscles fatigue on postural control in people with and without recurrent low back pain. Spine (Phila Pa

[56] Janssens L, Brumagne S, McConnell AK, et al. Proprioceptive changes impair balance control in individuals with chronic obstructive pulmonary disease. PLoS One. 2013;**8**(3):

[57] Brumagne S, Janssens L, Knapen S, et al. Persons with recurrent low back pain exhibit a

[58] Ito T, Sakai Y, Nakamura E, et al. Relationship between paraspinal muscle cross‐sec‐ tional area and relative proprioceptive weighting ratio of older persons with lumbar

[59] Ito T, Sakai Y, Kubo A, et al. The relationship between physical function and postural sway during local vibratory stimulation of middle‐aged people in the standing position.

rigid postural control strategy. Eur Spine J. 2008;**17**(9):1177–84.

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e57949.

361–6.

40 Clinical Physical Therapy

Additional information is available at the end of the chapter Hitoshi Asai

http://dx.doi.org/10.5772/67510 Additional information is available at the end of the chapter

#### Abstract

The mobility of the lumbar spine (anteversion and retroversion) may be reflected in seated pelvic mobility. When sitting with the soles of the feet in contact with the floor, friction may restrict the flexion of the knees and, consequently, the pelvic anteversion. In general, joint mobility declines with advancing age. Lumbar spine mobility in anteversion and retroversion also decreases with advancing age. The first half of this chapter is based on a study that investigated the relationship between age and the maximum pelvic anteversion and the retroversion angles in healthy volunteers. The measurements were performed with the subject in a sitting position with free knee movement. On the other hand, the sitto-stand movement is one of the most mechanically demanding tasks undertaken during daily activity. The sacral sitting posture, which is a characteristic posture of stroke patients, is not ideal for smoothly executing the sit-to-stand movement. Stroke patients may adopt this posture due to the need to increase sitting stability. The second half of this chapter discusses a study that investigated the relationship between the pelvic anteversion and retroversion angles and the ability of stroke patients to perform the sit-to-stand movement.

Keywords: pelvic movement, anteversion, retroversion, aging, stroke, sit-to-stand

#### 1. Introduction

Maintaining sagittal balance is important to both sitting and standing. Sagittal balance, or "neutral upright sagittal spinal alignment," is a postural goal of surgical, ergonomic, and physiotherapeutic intervention [1]. Kyphotic curvature of the spine negatively impacts the quality of life (QOL) in elderly people [2]. Kasukawa et al. reported that the sagittal balance was well maintained in subjects who had both a good thoracic range of motion (ROM) and

© 2017 The Author(s). Licensee InTech. 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.

© The Author(s). Licensee InTech. 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 eproduction in any medium, provided the original work is properly cited.

good lumbar ROM and back muscle strength, which indicates that these factors are also related in maintaining sagittal balance [2]. The clarification of the relationship between the QOL and abnormal posture in elderly individuals may help to improve the QOL through preventive methods and exercises [3]. Although the degree of lumbar lordosis when sitting has been shown to be weakly associated with age, lumbar lordosis was not found to be affected by lifestyle, the level of physical activity, or an individual's type of work [4]. Little is known about the sitting posture of elderly individuals in comparison with young individuals [5]; thus, investigating the effects of aging on the sagittal spinal and pelvic alignment in the sitting position is important for clarifying the relationship between pelvic movement and the QOL. Sitting positions are generally categorized into two types: the quiet sitting position and the functional sitting position. A person sits in the functional sitting position during (or when anticipating) physical activity. The functional sitting position therefore requires control in various sitting postures.

Multiple movements of the spine and pelvis are needed to maintain the various sitting positions. The relationship between the movements of the lumbar spine and pelvis has been investigated [5, 6]. The relationship between the pelvic inclination angle and lumbar spine lordosis was more distinct in the sitting position than in the standing position [5, 7]. Thus, lumbar spine mobility (kyphosis and lordosis) may be reflected in seated pelvic mobility. However, it has been reported that joint mobility is generally reduced by aging. The trunk mobility of elderly individuals is inferior to that of young people [8–10]. In particular, lumbar spine mobility in both lordosis and kyphosis decreases with aging [1, 11, 12]. In addition, Keorochana et al. suggested that the degeneration of the interspinous ligaments with aging is one of the factors that contributes to the low mobility of the lumbar spine [13]. Hence, the movement patterns of elderly individuals may be restricted when they are seated because there is less variety in their sitting positions in comparison with young subjects.

The pelvic tilt in the sagittal plane may be affected by flexion and the extension mobility of the hip joints, because the pelvis moves forward and backward around the hip joint as a pivotal axis in the seated position. Since the hamstring muscles originate at the ischial tuberosity of the pelvis, the tension in the hamstring muscles has an effect on the pelvic inclination angle in the sitting position [14, 15]. Thus, a forward pelvic tilt may increase the tension in the hamstring muscles when sitting with a fixed knee angle and the sole of the foot in contact with the floor. Connective tissue compliance is considered a major factor in musculoskeletal flexibility [16]. Muyor et al. [17] reported that the forward pelvic tilt angle increased after hamstring muscle stretching, and Feland et al. [16] confirmed that pelvic mobility in the sagittal plane increased in elderly people after hamstring muscle stretching. The increase in the tension in the hamstring muscles when sitting with the soles of the feet in contact with the floor may restrict the pelvic forward tilt. Thus, the free movement of the knees should be possible during pelvic movement when sagittal plane pelvic mobility is investigated with a subject in a sitting position. However, some sitting pelvic mobility studies have not clearly described foot contact with the floor or the knee joint positioning [6, 18].

On the other hand, the recovery of sitting balance is commonly assumed to be essential for obtaining independence in other vital functions such as reaching, sit-to-stand, and sitting down [19–21]. The early assessment and management of trunk control should be emphasized after stroke [22]. Many researchers have suggested that the trunk control or sitting balance of early stage stroke patients can predict a late stage activities of daily living (ADL) outcome [19, 22, 23]. The sit-to-stand task is frequently performed and this ability is considered a prerequisite for upright mobility and therefore, for performing other important daily activities such as locomotion [24, 25]. Riley et al. suggested that the sit-to-stand movement is the most mechanically demanding task undertaken during daily activity [26]. The sit-to-stand movement represents a common functional movement that is practiced in the early stage of rehabilitation [27].

good lumbar ROM and back muscle strength, which indicates that these factors are also related in maintaining sagittal balance [2]. The clarification of the relationship between the QOL and abnormal posture in elderly individuals may help to improve the QOL through preventive methods and exercises [3]. Although the degree of lumbar lordosis when sitting has been shown to be weakly associated with age, lumbar lordosis was not found to be affected by lifestyle, the level of physical activity, or an individual's type of work [4]. Little is known about the sitting posture of elderly individuals in comparison with young individuals [5]; thus, investigating the effects of aging on the sagittal spinal and pelvic alignment in the sitting position is important for clarifying the relationship between pelvic movement and the QOL. Sitting positions are generally categorized into two types: the quiet sitting position and the functional sitting position. A person sits in the functional sitting position during (or when anticipating) physical activity. The functional sitting position therefore requires control in

Multiple movements of the spine and pelvis are needed to maintain the various sitting positions. The relationship between the movements of the lumbar spine and pelvis has been investigated [5, 6]. The relationship between the pelvic inclination angle and lumbar spine lordosis was more distinct in the sitting position than in the standing position [5, 7]. Thus, lumbar spine mobility (kyphosis and lordosis) may be reflected in seated pelvic mobility. However, it has been reported that joint mobility is generally reduced by aging. The trunk mobility of elderly individuals is inferior to that of young people [8–10]. In particular, lumbar spine mobility in both lordosis and kyphosis decreases with aging [1, 11, 12]. In addition, Keorochana et al. suggested that the degeneration of the interspinous ligaments with aging is one of the factors that contributes to the low mobility of the lumbar spine [13]. Hence, the movement patterns of elderly individuals may be restricted when they are seated because

The pelvic tilt in the sagittal plane may be affected by flexion and the extension mobility of the hip joints, because the pelvis moves forward and backward around the hip joint as a pivotal axis in the seated position. Since the hamstring muscles originate at the ischial tuberosity of the pelvis, the tension in the hamstring muscles has an effect on the pelvic inclination angle in the sitting position [14, 15]. Thus, a forward pelvic tilt may increase the tension in the hamstring muscles when sitting with a fixed knee angle and the sole of the foot in contact with the floor. Connective tissue compliance is considered a major factor in musculoskeletal flexibility [16]. Muyor et al. [17] reported that the forward pelvic tilt angle increased after hamstring muscle stretching, and Feland et al. [16] confirmed that pelvic mobility in the sagittal plane increased in elderly people after hamstring muscle stretching. The increase in the tension in the hamstring muscles when sitting with the soles of the feet in contact with the floor may restrict the pelvic forward tilt. Thus, the free movement of the knees should be possible during pelvic movement when sagittal plane pelvic mobility is investigated with a subject in a sitting position. However, some sitting pelvic mobility studies have not clearly described foot contact

On the other hand, the recovery of sitting balance is commonly assumed to be essential for obtaining independence in other vital functions such as reaching, sit-to-stand, and sitting

there is less variety in their sitting positions in comparison with young subjects.

with the floor or the knee joint positioning [6, 18].

various sitting postures.

42 Clinical Physical Therapy

Stroke patients have less stability in the sitting position in comparison with age-matched healthy subjects [28–30]. The reason for this is explained in a number of reports. In stroke patients, the activity of the rectus abdominis and latissimus dorsi muscles on the affected side of the body is reduced and delayed in comparison to both the unaffected side and control subjects [31]. Moreover, the temporal synchronization between the pertinent muscular pairs in stroke patients is lower in comparison to healthy subjects [32]. The following factors can also be considered to be related to the sitting position: firstly, stroke patients cannot adequately flex the hip when the trunk extensor muscles are contracted; secondly, it is difficult to maintain the trunk in a vertical position when the subject is seated due to the insufficiency of the abdominal muscles [33]. Thus, when stroke patients attempt to perform the sit-to-stand movement with a retroverted pelvis and kyphotic trunk, the standing up action is affected due to the insufficiency of pelvic anteversion and trunk extension. In addition, Campbell et al. suggested that deficits in the muscle strength and trunk amplitude of stroke patients result in reduced pelvic mobility, apparently as a strategy to protect against a potential risk of loss of balance when reaching in the sitting position [34].

Numerous studies investigating trunk movement have considered the supine position as one segment, ignoring the complexity of intervertebral movement [35]. Campbell et al. indicated that little attention has been paid to how elderly persons coordinate the head, pelvis, and trunk during movement [34]. Studies on the sitting posture of stroke patients have a similar tendency. Few studies have investigated the movement of the spine and pelvis separately. Verheyden et al. reported on pelvic movement during lateral reach movements in the sitting position [36], and Messier et al. described the movements of the upper trunk and pelvis when subjects touched a target placed in front of them with the forehead [37]. To execute the sit-to-stand movement smoothly, the pelvis must be leaned forward to flex the hip joint, and the trunk must be flexed in order to: (1) use the hip extension moment; (2) reduce the knee extension moment; and (3) project the center of gravity within the base of support [38–43].

Pelvic mobility plays an important role in the sit-to-stand movement in elderly people and stroke patients.

This chapter first discusses the age-related changes in the maximum anteversion and retroversion of the pelvic angles in the sitting position [44] and then explores the relationship between the ability to perform the sit-to-stand movement and the maximum pelvic anteversion and retroversion angles in stroke patients [45].


**2. Materials and Methods**

LN:Mg polycrystalline powders were synthesized by a wet chemistry method. Nb(OH)5 (99.99%) was firstly weighted, and excess HCl (38%) was added into a container. Then, they were heated at 90 ◦C and stirred for 30 min. During this process, the mass of active Nb2O5·nH2O was precipitated. After being cooled, the observed white precipitate was NbOCl3, which should be completely dissolved by adding deionized water. Malic acid (C4H6O4, MA) as the ratio of (MA):(Nb) = 3:1 was added into the former solution and stirred. Then, the pH value of the suspension was adjusted to 8 by the addition of NH3·H2O to get solution A. The chemical reactions happened in producing solution A were as follows:

$$\text{Nb(OH)}\_{5} + 3\text{HCl} \rightarrow \text{NbOCl}\_{3} + 4\text{H}\_{2}\text{O} \tag{1}$$

$$\text{R 2NbCl}\_3 + (\text{n} + \text{3})\text{H}\_2\text{O} \rightarrow \text{Nb}\_2\text{O}\_5\cdot\text{nH}\_2\text{O} + \text{6HCl} \tag{2}$$

$$\text{Nb}\_2\text{O}\_5\text{-nH}\_2\text{O} + \text{MA} \rightarrow \text{Nb} - \text{MA} + \text{nH}\_2\text{O} \tag{3}$$

According to the congruent composition of (Li)/(Nb) = 48.38/51.62 and the selected doping concentration of MgO (0, 3 mol%, 5 mol%), Li2CO3 (99.99%) and MgO (99.99%) were weighted and dissolved by dilute HCl. Until no more bubbles produced, the pH value was adjusted to 8 by the addition of NH3·H2O to get solution B. Afterward, solutions A and B were mixed to be of high homogeneity by ultrasonic machine. The mixed solution was filtered and spray dried into powders. At last, the powders were sintered at 820 ◦C for 6 h to obtain LN:Mg polycrystalline powders.

Using the prepared LN:Mg polycrystalline powder, we firstly grew Ø1" LN:Mg crystals and served them as seed crystals continue to grow Ø2" LN crystals doped with different MgO concentration of 0, 3%, and 5 mol% by the Bridgman method with multi-crucible [31], which were labeled as LN, LN: Mg3, and LN: Mg5, respectively. The prepared LN: Mg polycrystalline powder was placed in three Pt crucibles with the same dimension of Ø50 mm × 100 mm. After putting them into three Al2O3 pipes with the dimension of Ø110 mm × 200 mm, they were simultaneously placed in a furnace. Some mullite fiber mixed with Al2O3 powders was used as the thermal insulation material to keep a stable thermal field. In order to be sufficiently melted, the LN: Mg polycrystalline powder was heated by medium-frequency induction and held at 100 ◦C above the melting point for 2 h. LN, LN: Mg3,

and LN: Mg5 crystals were grown in a sealed environment and along the c-axis. In the procedure of crystal growth, the falling rate was governed in the range of 0.5 mm/h to 1.0 mm/h. The vertical temperature gradient above the solid-melt interface was about 0.3 ◦C/mm, which was measured by using a thermocouple. In order to avoid the cracks occurring in large crystals, they were cooled down to room temperature at a low rate of 30 ◦C/h after the growth process. Finally, LN: Mg crystals with Ø2" in diameter and 40 mm in length were grown along the c axis. It was necessary to anneal the as-grown crystals at 1230 ◦C for 30 h to escape thermoelastic stress and improve optical homogeneity. The single-domain structure would be formed by polarization with an electric current density of 7 mA/cm2 for 20 min at 1190 ◦C. The 3 mm and 1 mm thick c-oriented plates were cut along the c-axis of the crystals and then polished to optical grade. The distance between the top and bottom part was about 4 cm.

The UV absorption edge wavelength and OH− spectra of 1-mm-thick plates were measured at room temperature on using a Beckman DU-8B spectrophotometer and Magna-560 Fourier transform IR spectrophotometer, respectively. High-resolution X-ray rocking curves of 3 mm plates were recorded by a Bruker HRXRD-5000 to examine the crystalline quality of LN: Mg3 and LN: Mg5 crystals. The refractive index of 1-mm-thick plates was also measured by METRICON 2010/M prism coupler at 632.8 nm to evaluate the optical homogeneity.