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Asymmetric reciprocity, reference wage formation, and the theory of wages and unemployment
Get PDFThis thesis contributes to the theory of wages and unemployment through an indepth theoretical analysis of firms' wage setting and hiring decisions and workers' perceptions of fairness and attitude in the production process.;Chapter 1 develops a microeconomic theory of wage setting behaviour based on contractual incompleteness, fairness, reciprocity and reference dependence and loss aversion in the evaluation of wage contracts by workers. The chapter makes the following contributions: it provides a theoretical explanation for wage rigidity in a dynamic environment; it offers a psychological foundation for asymmetric reciprocity, identifying loss aversion as the driver of negative reciprocity being stronger than positive reciprocity; and it analyses the implications of "asymmetric reference-dependent reciprocity" and anticipated wage rigidity for optimal wage setting and hiring behaviour.;Chapter 2 incorporates the theory developed in Chapter 1 into a canonical search and matching framework and analyses its macroeconomic implications. In so doing the chapter contributes to the literature of labour market fluctuations from a novel behavioural perspective. In contrast to existing theoretical results, in the presence of reference-dependent reciprocity the cyclicality of the hiring wage is shown to be irrelevant for the volatility of vacancies and unemployment.;Moreover, the novel behavioural aspects introduced turn out to be qualitatively and quantitatively important in determining the size of the surplus from new employment relationships. Finally, by considering the role of uncertainty, it is shown that the expectation by firms of downward wage rigidity dampens hiring incentives and increases the volatility of both job creation and unemployment;Chapter 3 explores the concept of the reference "fair" wage in depth. Building on a large body of research that has explored the concepts of fairness, reference dependence, and social norms and identity, this chapter develops a general, and portable, analytical framework to model reference wage formation. Several inherent properties of the reference wage are formalised: the intrinsic tendency of workers to adapt their reference wage over time; the role of readily available information, which can also be "manipulated" by the firmand/or third parties; and asymmetries in fairness evaluations.;This framework is applied to study the implications of asymmetric partial adaptation of the reference wage for wage and reciprocity dynamics; and the effect of relative wage comparisons between newly hired and incumbent workers for the cyclical behaviour of vacancies and unemployment.This thesis contributes to the theory of wages and unemployment through an indepth theoretical analysis of firms' wage setting and hiring decisions and workers' perceptions of fairness and attitude in the production process.;Chapter 1 develops a microeconomic theory of wage setting behaviour based on contractual incompleteness, fairness, reciprocity and reference dependence and loss aversion in the evaluation of wage contracts by workers. The chapter makes the following contributions: it provides a theoretical explanation for wage rigidity in a dynamic environment; it offers a psychological foundation for asymmetric reciprocity, identifying loss aversion as the driver of negative reciprocity being stronger than positive reciprocity; and it analyses the implications of "asymmetric reference-dependent reciprocity" and anticipated wage rigidity for optimal wage setting and hiring behaviour.;Chapter 2 incorporates the theory developed in Chapter 1 into a canonical search and matching framework and analyses its macroeconomic implications. In so doing the chapter contributes to the literature of labour market fluctuations from a novel behavioural perspective. In contrast to existing theoretical results, in the presence of reference-dependent reciprocity the cyclicality of the hiring wage is shown to be irrelevant for the volatility of vacancies and unemployment.;Moreover, the novel behavioural aspects introduced turn out to be qualitatively and quantitatively important in determining the size of the surplus from new employment relationships. Finally, by considering the role of uncertainty, it is shown that the expectation by firms of downward wage rigidity dampens hiring incentives and increases the volatility of both job creation and unemployment;Chapter 3 explores the concept of the reference "fair" wage in depth. Building on a large body of research that has explored the concepts of fairness, reference dependence, and social norms and identity, this chapter develops a general, and portable, analytical framework to model reference wage formation. Several inherent properties of the reference wage are formalised: the intrinsic tendency of workers to adapt their reference wage over time; the role of readily available information, which can also be "manipulated" by the firmand/or third parties; and asymmetries in fairness evaluations.;This framework is applied to study the implications of asymmetric partial adaptation of the reference wage for wage and reciprocity dynamics; and the effect of relative wage comparisons between newly hired and incumbent workers for the cyclical behaviour of vacancies and unemployment
Length-structured approach to fisheries stock assessment
Get PDFModern fishing fleets have the capacity to over-exploit fish stocks. Inaccurate assessments could overestimate the stock size and as a result Total Allowable Catches (TAC) are set too high for sustainable stock conservation. Fisheries management need robust and reliable stock assessments to ensure that the species and environmental effect of fishing is sustainable. Since the demand for ecosystem based approaches to management has increased, the needs for improved estimates of un-assessed abundance have risen. Managers simply need to know how many fish left in the see and how much to limit the fishermen to fish to have sustainable fisheries. Therefore, accurate assessment of the market as well as by-catch stocks and records of true landings and discards are critical aspects of the scientific advice to the fisheries managers to accurately set TACs. Here, we consider the marine species that are left un-assessed. That is because they cannot be assessed by the existing methods. We therefore sought to fill the key gap with this matter. This thesis has five key elements. First we reviewed the stock assessment method with the emphasis on the length-structured models. Second, we produced a population model (so called survey-landings model) to make the use of survey frequency data extracted from International Bottom Trawl Survey and total annual landed biomass from commercial reports. Third, within a twin-experiment context and sensitivity analysis the model was assessed for accuracy and robustness in variability in initial parameter values and observational noise. Forth, applying the survey-landings model the population dynamics of the North Sea haddock was assessed and the results were compared with the International Council for Exploitation of the Sea assessment. Fifth, after the model proved to be reliable it is used as an alternative for age- or catch-at-length model, the population of the North Sea grey gurnards were modelled with confidence. This model enabled un-assessed species such as grey gurnards to be modelled and assessed for the first time.Modern fishing fleets have the capacity to over-exploit fish stocks. Inaccurate assessments could overestimate the stock size and as a result Total Allowable Catches (TAC) are set too high for sustainable stock conservation. Fisheries management need robust and reliable stock assessments to ensure that the species and environmental effect of fishing is sustainable. Since the demand for ecosystem based approaches to management has increased, the needs for improved estimates of un-assessed abundance have risen. Managers simply need to know how many fish left in the see and how much to limit the fishermen to fish to have sustainable fisheries. Therefore, accurate assessment of the market as well as by-catch stocks and records of true landings and discards are critical aspects of the scientific advice to the fisheries managers to accurately set TACs. Here, we consider the marine species that are left un-assessed. That is because they cannot be assessed by the existing methods. We therefore sought to fill the key gap with this matter. This thesis has five key elements. First we reviewed the stock assessment method with the emphasis on the length-structured models. Second, we produced a population model (so called survey-landings model) to make the use of survey frequency data extracted from International Bottom Trawl Survey and total annual landed biomass from commercial reports. Third, within a twin-experiment context and sensitivity analysis the model was assessed for accuracy and robustness in variability in initial parameter values and observational noise. Forth, applying the survey-landings model the population dynamics of the North Sea haddock was assessed and the results were compared with the International Council for Exploitation of the Sea assessment. Fifth, after the model proved to be reliable it is used as an alternative for age- or catch-at-length model, the population of the North Sea grey gurnards were modelled with confidence. This model enabled un-assessed species such as grey gurnards to be modelled and assessed for the first time
Evaluation of the role of mast cells in parasitic infection
Get PDFMast cells (MCs) are important for controlling both bacterial and parasitic infections, including those caused by helminths. However, their role in combatting these infections is unclear. MCs have been shown to be essential for the successful expulsion of Trichinella spiralis worms and play a role in mounting the immune response towards a T helper 2 type. Intestinal infection with parasitic worms is associated with mastocytosis and the activation and release of specific mediators and cytokines. In this case, MCs play an essential role in the successful expulsion of gastrointestinal worms via their release of mediators that serve the central function of protecting a host from these parasites. Specifically, the functions of MCs in the expulsion of T. spiralis were investigated using MC deficient c-kit mutant KitW/W-v(W/W-v) models. However, in addition to MC deficiency, these mice have a number of other abnormalities, including anaemia and a lack of interstitial cells of Cajal. Hence, there is a need to identify a model of MC deficiency that is not associated with other abnormalities that could affect the interpretation of results. The aim of the present study was to investigate the role of MCs in the immune response of mice to a parasitic infection of T. spiralis. Immune responses were explored in two recently developed strains of MC-deficient mice, the c-kit model C57BL/6-KitW-sh/W-sh (Wsh/Wsh) mice and an inducible mast cell-deficient model, Mas-TRECK, to determine the role of mast cells in protection against the parasite. These mice were infected with T. spiralis larvae, and the progression of the infection and the immune responses generated were examined via the enumeration of worms and the analysis of the associated intestinal pathology, cytokine production and antibody responses. The results obtained from mast cell deficient Wsh/Wsh mice with low-level infection resulted in a significant worm burden in these mice compared to wild-type mice that showed complete expulsion of the parasite. This suggests that the delay was potentially caused by dose dependent effect as a high dose did not show a significant delay in the expulsion of T. spiralis worms. In addition, the development of enteropathy and lengths of both villi and crypts were similar in both the lower and higher infection groups, in both wild-type and Wsh/Wsh mice.;The immune responses were similar in wild-type and Wsh/Wsh mice as assessed by antigen-specific IgG1 levels, the total IgE levels and IL-4 levels. Moreover, Wsh/Wsh mice in both levels of infection were able to induce a significant marked mastocytosis, but they did not have significantly lower levels of mMCP-1 compared to wild-type mice. The results obtained from Mas-TRECK mice models showed no statistically significant differences between these mice and wild-type mice in the expulsion of T. spiralis worms. The enteropathy in Mas-TRECK mice following infection with T.spiralis was not significantly improved. In addition, the infection of Mas-TRECK mice did not induce a change in IgG2a levels compared with BALB/c mice, and no significant differences were observed in IgE levels or IL-4 levels in Mas-TRECK mice, compared with wild-type. In addition, Mas-TRECK were able to induce mastocytosis and did not have significantly lower levels of mMCP-1 following infection with T. spiralis, although they are considered to be MC-deficient, which suggests that MMCs may not be completely depleted in these mice. Mast cell activation was assessed using IgE-dependent MC activation to evaluate the ability of helminth antigens to activate mast cells through an immunoglobulin independent mechanism. An in vitro culture of bone marrow-derived mast cells(BMMCs) and peritoneal mast cells (PCMCs) used. Although cultured human MCs require stem cell factor (SCF) for growth, the expansion and growth of mouse MCs from bone marrow progenitors in the absence of SCF can be maintained with IL-3. It was found that stimulated PCMCs with Trichinella spiralis antigen (T. Ag) alone could activate mast cells to release IL-4 in all strains of mice. Moreover, the activation of PCMCs could be observed in the presence and absence of IgE, andC57BL/6 mice showed the greatest response to the stimulation and activation of PCMCs. BMMCs stimulated with helminth antigens led to similar secretions of mediators to those observed in wild-type mice, and all four strains of mice tended to secrete similar levels of mMCP-1. Overall, the present study concludes that MCs are crucial for protection against and expulsion of T. spiralis. However, it is evident that Wsh/Wsh and Mas-TRECK MC deficient mice are not entirely deficient in mucosal MC. Further studies are required to evaluate the benefits of different MC-deficient strains of mice and, particularly, to determine whether other abnormalities could have potentially affected the results of the present study.Mast cells (MCs) are important for controlling both bacterial and parasitic infections, including those caused by helminths. However, their role in combatting these infections is unclear. MCs have been shown to be essential for the successful expulsion of Trichinella spiralis worms and play a role in mounting the immune response towards a T helper 2 type. Intestinal infection with parasitic worms is associated with mastocytosis and the activation and release of specific mediators and cytokines. In this case, MCs play an essential role in the successful expulsion of gastrointestinal worms via their release of mediators that serve the central function of protecting a host from these parasites. Specifically, the functions of MCs in the expulsion of T. spiralis were investigated using MC deficient c-kit mutant KitW/W-v(W/W-v) models. However, in addition to MC deficiency, these mice have a number of other abnormalities, including anaemia and a lack of interstitial cells of Cajal. Hence, there is a need to identify a model of MC deficiency that is not associated with other abnormalities that could affect the interpretation of results. The aim of the present study was to investigate the role of MCs in the immune response of mice to a parasitic infection of T. spiralis. Immune responses were explored in two recently developed strains of MC-deficient mice, the c-kit model C57BL/6-KitW-sh/W-sh (Wsh/Wsh) mice and an inducible mast cell-deficient model, Mas-TRECK, to determine the role of mast cells in protection against the parasite. These mice were infected with T. spiralis larvae, and the progression of the infection and the immune responses generated were examined via the enumeration of worms and the analysis of the associated intestinal pathology, cytokine production and antibody responses. The results obtained from mast cell deficient Wsh/Wsh mice with low-level infection resulted in a significant worm burden in these mice compared to wild-type mice that showed complete expulsion of the parasite. This suggests that the delay was potentially caused by dose dependent effect as a high dose did not show a significant delay in the expulsion of T. spiralis worms. In addition, the development of enteropathy and lengths of both villi and crypts were similar in both the lower and higher infection groups, in both wild-type and Wsh/Wsh mice.;The immune responses were similar in wild-type and Wsh/Wsh mice as assessed by antigen-specific IgG1 levels, the total IgE levels and IL-4 levels. Moreover, Wsh/Wsh mice in both levels of infection were able to induce a significant marked mastocytosis, but they did not have significantly lower levels of mMCP-1 compared to wild-type mice. The results obtained from Mas-TRECK mice models showed no statistically significant differences between these mice and wild-type mice in the expulsion of T. spiralis worms. The enteropathy in Mas-TRECK mice following infection with T.spiralis was not significantly improved. In addition, the infection of Mas-TRECK mice did not induce a change in IgG2a levels compared with BALB/c mice, and no significant differences were observed in IgE levels or IL-4 levels in Mas-TRECK mice, compared with wild-type. In addition, Mas-TRECK were able to induce mastocytosis and did not have significantly lower levels of mMCP-1 following infection with T. spiralis, although they are considered to be MC-deficient, which suggests that MMCs may not be completely depleted in these mice. Mast cell activation was assessed using IgE-dependent MC activation to evaluate the ability of helminth antigens to activate mast cells through an immunoglobulin independent mechanism. An in vitro culture of bone marrow-derived mast cells(BMMCs) and peritoneal mast cells (PCMCs) used. Although cultured human MCs require stem cell factor (SCF) for growth, the expansion and growth of mouse MCs from bone marrow progenitors in the absence of SCF can be maintained with IL-3. It was found that stimulated PCMCs with Trichinella spiralis antigen (T. Ag) alone could activate mast cells to release IL-4 in all strains of mice. Moreover, the activation of PCMCs could be observed in the presence and absence of IgE, andC57BL/6 mice showed the greatest response to the stimulation and activation of PCMCs. BMMCs stimulated with helminth antigens led to similar secretions of mediators to those observed in wild-type mice, and all four strains of mice tended to secrete similar levels of mMCP-1. Overall, the present study concludes that MCs are crucial for protection against and expulsion of T. spiralis. However, it is evident that Wsh/Wsh and Mas-TRECK MC deficient mice are not entirely deficient in mucosal MC. Further studies are required to evaluate the benefits of different MC-deficient strains of mice and, particularly, to determine whether other abnormalities could have potentially affected the results of the present study
Electrodeposition of copper using additive-containing low metal ion concentration electrolytes for EnFACE applications
Get PDFIn the past decade a new electrodeposition process called Electrochemical nano and micro Fabrication by flow and Chemistry (EnFACE) was developed which enabled mask-less pattern transfers onto a metallic substrate. EnFACE uses a novel acid-free, additive-free plating electrolyte containing low concentrations of metal salts (0.1 MCuSO4), as the process requires electroplating under conditions of fast kinetics and low electrolyte conductivity. However, for electronic applications,industry requires the use of additives, which improve deposit properties such as thickness uniformity, strength, ductility, and conductivity. The use of pulsed current is also known to improve deposit properties such as grain structure, mechanical strength and throwing power. Therefore, in order to use EnFACE for fabrication of industrially useful products, the effect of additives on the electrochemical behaviour and deposit properties of this process needs to be assessed. In addition, the influence of current modulation; i.e. direct current vs pulsed current, on deposit properties also warrants investigation. Potentiodynamic polarisation experiments were performed on additive-free and additive-containing EnFACE electrolyte (0.1 M CuSO₄). The additives tested were Copper Gleam A, Copper Gleam B, and chloride ions (Cl⁻). The effect of two parameters: (i) additive type and (ii) additive concentration, on cathode polarisation were studied.Copper films were electroplated on stainless steel substrates from electrolytes containing different concentrations of plating additives (0%, 17%, 33%, 50%, 100%,200% of the industry recommended additive concentration). Both direct current (DC)ABSTRACT|ii and pulsed current (PC) plating were used. The deposit was characterised using scanning electron microscope (SEM), electron back scattered diffraction (EBSD),tensile test machine (UTM), four-point probe and X-ray diffraction (XRD).Cathode polarisation occurred when the additives were used individually. Thecombination of Copper Gleam B and Cl- suggested synergistic inhibition, particularly in the diffusion-limited region. The addition of Copper Gleam A to the CopperGleam B-Cl⁻ mix increased the limiting current and suggested plating acceleration.These effects are interpreted in terms of the adsorption-desorption behavior of the additives on the cathode surface. SEM and EBSD images indicated that additives caused a concentration dependent decrease in the grain size of the deposit in both the DC and PC plated deposit. This grain refinement resulted in an increase in yield and tensile strength,but reduced the ductility and resistivity of deposits. The PC-plated copper from theEnFACE electrolytes generally possessed better mechanical properties than its DC-plated counterparts, though both plating modes created copper films that can meet industry standards. The optimum additive concentration for the EnFACE electrolyte was 50% of the recommended value when using DC plating; while the optimum was only 33% when using PC plating.In the past decade a new electrodeposition process called Electrochemical nano and micro Fabrication by flow and Chemistry (EnFACE) was developed which enabled mask-less pattern transfers onto a metallic substrate. EnFACE uses a novel acid-free, additive-free plating electrolyte containing low concentrations of metal salts (0.1 MCuSO4), as the process requires electroplating under conditions of fast kinetics and low electrolyte conductivity. However, for electronic applications,industry requires the use of additives, which improve deposit properties such as thickness uniformity, strength, ductility, and conductivity. The use of pulsed current is also known to improve deposit properties such as grain structure, mechanical strength and throwing power. Therefore, in order to use EnFACE for fabrication of industrially useful products, the effect of additives on the electrochemical behaviour and deposit properties of this process needs to be assessed. In addition, the influence of current modulation; i.e. direct current vs pulsed current, on deposit properties also warrants investigation. Potentiodynamic polarisation experiments were performed on additive-free and additive-containing EnFACE electrolyte (0.1 M CuSO₄). The additives tested were Copper Gleam A, Copper Gleam B, and chloride ions (Cl⁻). The effect of two parameters: (i) additive type and (ii) additive concentration, on cathode polarisation were studied.Copper films were electroplated on stainless steel substrates from electrolytes containing different concentrations of plating additives (0%, 17%, 33%, 50%, 100%,200% of the industry recommended additive concentration). Both direct current (DC)ABSTRACT|ii and pulsed current (PC) plating were used. The deposit was characterised using scanning electron microscope (SEM), electron back scattered diffraction (EBSD),tensile test machine (UTM), four-point probe and X-ray diffraction (XRD).Cathode polarisation occurred when the additives were used individually. Thecombination of Copper Gleam B and Cl- suggested synergistic inhibition, particularly in the diffusion-limited region. The addition of Copper Gleam A to the CopperGleam B-Cl⁻ mix increased the limiting current and suggested plating acceleration.These effects are interpreted in terms of the adsorption-desorption behavior of the additives on the cathode surface. SEM and EBSD images indicated that additives caused a concentration dependent decrease in the grain size of the deposit in both the DC and PC plated deposit. This grain refinement resulted in an increase in yield and tensile strength,but reduced the ductility and resistivity of deposits. The PC-plated copper from theEnFACE electrolytes generally possessed better mechanical properties than its DC-plated counterparts, though both plating modes created copper films that can meet industry standards. The optimum additive concentration for the EnFACE electrolyte was 50% of the recommended value when using DC plating; while the optimum was only 33% when using PC plating
Propaganda and the presidency : an analysis of Lyndon B. Johnson's media relations, 1963-1968
Get PDFLyndon Johnson's presidency saw a great shift in the balance of domestic politics in the United States. While there was great merit to many of his domestic aspirations the erosion of his own credibility damaged the standing of the Democratic Party and ensured that the Republicans swept back into office in 1968. The Democrats saw only one president - Jimmy Carter - elected between 1968 and 1992 following Johnson's presidency and four of the subsequent five presidents were Republicans; Richard Nixon, Gerald Ford, Ronald Reagan and George H. W. Bush.;The failure of the Great Society and subsequent inflation crisis caused in part by spending on domestic concerns and Vietnam were influential on a general upswing in conservatism, and although it should not be argued that the Johnson administration was wholly responsible for this, there is at least some evidence to suggest that a grassroots rise in conservatism happened under Johnson's watch. The legacy of the administration was to usher in an era of suspicion and mistrust of the presidency, which would ultimately culminate in the Watergate Scandal under his successor Nixon.;Robert Dallek perhaps best summed up the Johnson presidency when he said, 'Whatever impulse future historians may have to pigeonhole Johnson as a near great, average, or failed President, I am confident that a close review of his time in office will leave them reluctant to put a single stamp on his term.' This is certainly true. Johnson is incredibly difficult to categorise as a president, with possibly the best description of his immediate legacy coming from Newsweek columnist Charles Roberts, following his death in 1973:;He leaves office a man whose epitaph will some day defy the confines of even a Texas-size tombstone: the most militant civil-rights advocate ever to occupy the White House, reviled by negro militants; a Southerner scorned by Southerners as a turncoat; a liberal despised by liberals despite the fact he achieved most of what they sought for thirty years; a friend of education rejected by intellectuals; a compromiser who could not compromise a war ten thousand miles away; a consensus-seeker who in the clutch abandoned his consensus rather than his convictions; a power hungry partisan politician who, in the end, shunned power and partisanship to achieve national unity.;There is no question that Lyndon Johnson is an important president, and his achievements with Medicare, civil rights legislation and anti-poverty acts were monumental. His influence on the presidency and politics in the years following his time in office should not be underestimated. What he was not however, was a man who could use the press to his advantage. Johnson presided over an era of changing attitudes and a more open and technologically advanced press than had existed in America prior to the 1960s. As we have seen, he consistently showed a short-term, reactive strategy toward dealing with press coverage and sliding approval ratings, and with each reaction and each ill-thought-out response to political problems, he created further issues for himself as his presidency went on.;This was evident in his planning for the 1964 election, when he positioned himself as the anti-war candidate against Barry Goldwater's hard-line views, even while he knew that escalation in Vietnam was assured. It was apparent in 1965, when James Greenfield criticised the administration for only meeting the crisis of the moment and not looking further ahead. It was clear in 1966, when the press openly reported on the credibility gap between Johnson and the people. By the time the administration took note and conducted what might be termed as a public relations offensive in late 1967, it was too late. In their assessments of how well the country was doing, they failed to look forward and see what reports already told them; the Tet Offensive of January 1968 was already being foreshadowed by enemy actions.;Tet shattered the goodwill that Johnson earned with his most pro-active strategy, and permanently ruined his credibility with the American people. While there is undoubtedly an argument to be made that external circumstances and the political volatility of the 1960s had an effect on how pro-active the president could be in his press dealings, the administration failed to effectively organise a strategy to propagandise the policies of the presidency and ultimately that failure lay chiefly with Lyndon B Johnson, himself.Lyndon Johnson's presidency saw a great shift in the balance of domestic politics in the United States. While there was great merit to many of his domestic aspirations the erosion of his own credibility damaged the standing of the Democratic Party and ensured that the Republicans swept back into office in 1968. The Democrats saw only one president - Jimmy Carter - elected between 1968 and 1992 following Johnson's presidency and four of the subsequent five presidents were Republicans; Richard Nixon, Gerald Ford, Ronald Reagan and George H. W. Bush.;The failure of the Great Society and subsequent inflation crisis caused in part by spending on domestic concerns and Vietnam were influential on a general upswing in conservatism, and although it should not be argued that the Johnson administration was wholly responsible for this, there is at least some evidence to suggest that a grassroots rise in conservatism happened under Johnson's watch. The legacy of the administration was to usher in an era of suspicion and mistrust of the presidency, which would ultimately culminate in the Watergate Scandal under his successor Nixon.;Robert Dallek perhaps best summed up the Johnson presidency when he said, 'Whatever impulse future historians may have to pigeonhole Johnson as a near great, average, or failed President, I am confident that a close review of his time in office will leave them reluctant to put a single stamp on his term.' This is certainly true. Johnson is incredibly difficult to categorise as a president, with possibly the best description of his immediate legacy coming from Newsweek columnist Charles Roberts, following his death in 1973:;He leaves office a man whose epitaph will some day defy the confines of even a Texas-size tombstone: the most militant civil-rights advocate ever to occupy the White House, reviled by negro militants; a Southerner scorned by Southerners as a turncoat; a liberal despised by liberals despite the fact he achieved most of what they sought for thirty years; a friend of education rejected by intellectuals; a compromiser who could not compromise a war ten thousand miles away; a consensus-seeker who in the clutch abandoned his consensus rather than his convictions; a power hungry partisan politician who, in the end, shunned power and partisanship to achieve national unity.;There is no question that Lyndon Johnson is an important president, and his achievements with Medicare, civil rights legislation and anti-poverty acts were monumental. His influence on the presidency and politics in the years following his time in office should not be underestimated. What he was not however, was a man who could use the press to his advantage. Johnson presided over an era of changing attitudes and a more open and technologically advanced press than had existed in America prior to the 1960s. As we have seen, he consistently showed a short-term, reactive strategy toward dealing with press coverage and sliding approval ratings, and with each reaction and each ill-thought-out response to political problems, he created further issues for himself as his presidency went on.;This was evident in his planning for the 1964 election, when he positioned himself as the anti-war candidate against Barry Goldwater's hard-line views, even while he knew that escalation in Vietnam was assured. It was apparent in 1965, when James Greenfield criticised the administration for only meeting the crisis of the moment and not looking further ahead. It was clear in 1966, when the press openly reported on the credibility gap between Johnson and the people. By the time the administration took note and conducted what might be termed as a public relations offensive in late 1967, it was too late. In their assessments of how well the country was doing, they failed to look forward and see what reports already told them; the Tet Offensive of January 1968 was already being foreshadowed by enemy actions.;Tet shattered the goodwill that Johnson earned with his most pro-active strategy, and permanently ruined his credibility with the American people. While there is undoubtedly an argument to be made that external circumstances and the political volatility of the 1960s had an effect on how pro-active the president could be in his press dealings, the administration failed to effectively organise a strategy to propagandise the policies of the presidency and ultimately that failure lay chiefly with Lyndon B Johnson, himself
The synthesis and testing of fast switching, novel conjugated polymers for electrochromic applications
Get PDFModern technology is an essential aspect of our everyday lifestyle being vitally important to lighting, mobile phones, laptops, toys etc. The majority of these gadgets concentrate on visual electronic displays as a key selling feature. Hence, industry is in constant competition to excel while delivering new consumer demands of higher colouration efficiency, faster response times, inexpensive yet robust hardware, flexible displays and with the possibility of incorporating electronics into textiles. Traditionally, inorganic small molecules were extensively used for optical displays devices such as cathode ray tubes, liquid crystal displays, light emitting diiodes [sic] and plasma screens. However, in the past decade, significant progress in polymer electrochromism has shown many organic electroactive polymers to have the potential to satisfy the above consumer demands. Electrochromic materials (EC) have the ability to undergo a reversible colour transformation switch upon electrochemical doping, such as colour bleaching transformations. Herein, this thesis discusses how organic chemistry facilitates the advantage of structurally modifying monomeric heterocyclics to fine tune materials with interesting optical and physical properties. The polymeric form of an teraryl monomer containing a 1,4-dithiin-furan illustrated superior switching performances and electrochromic properties when compared to its parent poly 3,4-ethylene dioxythiophene (PEDOT). Poly(dithienylfuran) films displayed fast switching and reversible colour transformation at high colour contrast (CE = 212 cm2 C-1 cf. 183 cm2 C_1 for PEDOT at 95% optical switch). Formerly overlooked furan materials in organic electronics was revisted here, in which a polyfuran substituted at the 2,3-positions with an S-alkylated dithiin unit, was studied. The employment of the dithiin moiety provides intrinsic additional electroactivity, as well as a functional handle for substitution with alkyl groups, enhancing the processability of the polymer. The new polymer is compared with the closely related and well-established literature compounds PEDOT and PEDTT as well-studied, highly chalcogenated polythiophenes. The electrochromism phenomenon is not only of importance for visual optical displays but also has the potential for extended application in telecommunications with electromagnetic responses into the near infra-red (NIR) region. Herein, describe a series of symmetric and asymmetric chalcogenated azomethine monomers, robustly exherting electrochemical activity within the NIR.Modern technology is an essential aspect of our everyday lifestyle being vitally important to lighting, mobile phones, laptops, toys etc. The majority of these gadgets concentrate on visual electronic displays as a key selling feature. Hence, industry is in constant competition to excel while delivering new consumer demands of higher colouration efficiency, faster response times, inexpensive yet robust hardware, flexible displays and with the possibility of incorporating electronics into textiles. Traditionally, inorganic small molecules were extensively used for optical displays devices such as cathode ray tubes, liquid crystal displays, light emitting diiodes [sic] and plasma screens. However, in the past decade, significant progress in polymer electrochromism has shown many organic electroactive polymers to have the potential to satisfy the above consumer demands. Electrochromic materials (EC) have the ability to undergo a reversible colour transformation switch upon electrochemical doping, such as colour bleaching transformations. Herein, this thesis discusses how organic chemistry facilitates the advantage of structurally modifying monomeric heterocyclics to fine tune materials with interesting optical and physical properties. The polymeric form of an teraryl monomer containing a 1,4-dithiin-furan illustrated superior switching performances and electrochromic properties when compared to its parent poly 3,4-ethylene dioxythiophene (PEDOT). Poly(dithienylfuran) films displayed fast switching and reversible colour transformation at high colour contrast (CE = 212 cm2 C-1 cf. 183 cm2 C_1 for PEDOT at 95% optical switch). Formerly overlooked furan materials in organic electronics was revisted here, in which a polyfuran substituted at the 2,3-positions with an S-alkylated dithiin unit, was studied. The employment of the dithiin moiety provides intrinsic additional electroactivity, as well as a functional handle for substitution with alkyl groups, enhancing the processability of the polymer. The new polymer is compared with the closely related and well-established literature compounds PEDOT and PEDTT as well-studied, highly chalcogenated polythiophenes. The electrochromism phenomenon is not only of importance for visual optical displays but also has the potential for extended application in telecommunications with electromagnetic responses into the near infra-red (NIR) region. Herein, describe a series of symmetric and asymmetric chalcogenated azomethine monomers, robustly exherting electrochemical activity within the NIR
Exploring biomimetic catalysts for alcohol generation
Get PDFThis thesis was previously restricted to Strathclyde users only from 1st September 2017 until 1 September 2022.The direct, selective and efficient functionalization of unactivated C-H bonds, such as those in naturally abundant hydrocarbons, remains one of the most difficult challenges in modern chemistry. However, in the last fifteen years much effort has been expended in developing various biomimetic catalysts that can perform the same functionalizations as those enzymes observed in nature.;This review discusses homogeneous monoiron and diiron catalysts, supported by various types of ligands and gives an up to date comparison on their hydroxylation reactivities with hydrocarbon substrates. The key intermediates involved in the reaction mechanisms are highlighted and those crucial steps such as hydrogen atom abstraction and OH rebound are investigated in order to rationalise how a catalyst's design influences its reactivity and also its stability.The direct, selective and efficient functionalization of unactivated C-H bonds, such as those in naturally abundant hydrocarbons, remains one of the most difficult challenges in modern chemistry. However, in the last fifteen years much effort has been expended in developing various biomimetic catalysts that can perform the same functionalizations as those enzymes observed in nature.;This review discusses homogeneous monoiron and diiron catalysts, supported by various types of ligands and gives an up to date comparison on their hydroxylation reactivities with hydrocarbon substrates. The key intermediates involved in the reaction mechanisms are highlighted and those crucial steps such as hydrogen atom abstraction and OH rebound are investigated in order to rationalise how a catalyst's design influences its reactivity and also its stability
Towards non-invasive characterisation of re-endothelialisation and restenosis following coronary stenting : an in vitro investigation using impedance spectroscopy
Get PDFPreviously held under moratorium from 19th October 2017 until 19th October 2022.Following the permanent implantation of a coronary stent, optimal arterial wall healing is characterised by re-endothelialisation, the regrowth of a functional Endothelial Cell (EC) monolayer over the exposed stent surface. However incomplete re-endothelialisation, increases the risk of stent thrombosis which can cause vessel narrowing to reoccur. Previous research has suggested that the stent itself could be used as an electrode and when combined with non-invasive impedance spectroscopy techniques monitor post stenting healing. This could then inform clinicians on cell regrowth without the need for invasive imaging techniques. This study investigated the feasibility of the concept using 3 in vitro models representing potential cellular regrowth scenarios: re-endothelialisation (ECs), smooth muscle cell (SMCs) proliferation and co-culture (ECs and SMCs). -- Primary porcine ECs and SMCs were seeded onto platinum black electrodes and a bespoke impedance spectroscopy system used to carry out automated measurements for time periods of up to 10 days. Endothelium function was assessed through the measurement of the impedance response of confluent EC monolayers to the addition of either a gap junction enhancer, dipyridamole, or an inhibitor (heptanol or carbenoxolone). -- The results show that confluent, stent surface comparable populations of SMCs, ECs and co-culture of both cell types gives rise to distinct impedance signatures, most evident in the reactance component of impedance. This provides a potential method of non-invasively characterising the two cell types. Gap junction inhibition of EC monolayers dose dependently reduced total impedance. Conversely dipyridamole’s enhancing effect on gap junction formation caused an increase in total impedance. These novel findings show the importance of intercellular gap junction communication in the maintenance of the endothelial barrier function. Overall, the results demonstrate the potential of impedance spectroscopy in characterising vascular healing and endothelium function and could, in the future, provide clinically useful information in the development of new stents.Following the permanent implantation of a coronary stent, optimal arterial wall healing is characterised by re-endothelialisation, the regrowth of a functional Endothelial Cell (EC) monolayer over the exposed stent surface. However incomplete re-endothelialisation, increases the risk of stent thrombosis which can cause vessel narrowing to reoccur. Previous research has suggested that the stent itself could be used as an electrode and when combined with non-invasive impedance spectroscopy techniques monitor post stenting healing. This could then inform clinicians on cell regrowth without the need for invasive imaging techniques. This study investigated the feasibility of the concept using 3 in vitro models representing potential cellular regrowth scenarios: re-endothelialisation (ECs), smooth muscle cell (SMCs) proliferation and co-culture (ECs and SMCs). -- Primary porcine ECs and SMCs were seeded onto platinum black electrodes and a bespoke impedance spectroscopy system used to carry out automated measurements for time periods of up to 10 days. Endothelium function was assessed through the measurement of the impedance response of confluent EC monolayers to the addition of either a gap junction enhancer, dipyridamole, or an inhibitor (heptanol or carbenoxolone). -- The results show that confluent, stent surface comparable populations of SMCs, ECs and co-culture of both cell types gives rise to distinct impedance signatures, most evident in the reactance component of impedance. This provides a potential method of non-invasively characterising the two cell types. Gap junction inhibition of EC monolayers dose dependently reduced total impedance. Conversely dipyridamole’s enhancing effect on gap junction formation caused an increase in total impedance. These novel findings show the importance of intercellular gap junction communication in the maintenance of the endothelial barrier function. Overall, the results demonstrate the potential of impedance spectroscopy in characterising vascular healing and endothelium function and could, in the future, provide clinically useful information in the development of new stents
The synthesis of stable nanotags for the detection of biomolecules using surface enhanced Raman scattering
Get PDFThis thesis was previously restricted to Strathclyde users only until 1st November 2022.Artificial enzymes have become an increasingly interesting area of research due to their many advantages over natural protein enzymes which are expensive, difficult to isolate and unable to stand harsh environments. An important area of this research involves using metal nanoparticles as artificial enzymes, known as nanozymes, which exhibit peroxidase-like activity enabling them to catalyse the oxidation of substrates such as 3,3',5,5'-tetramethylbenzidine (TMB) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) and in the presence of hydrogen peroxide (H2O2). This yields a colorimetric response which can be characterised using ultraviolet-visible (UV-vis) spectroscopy, Resonance Raman scattering (RRS) and surface enhanced resonance Raman scattering (SERRS). Nanozymes have been applied to various different applications, some of which are explored in this thesis. The overall aim of this research was to investigate the synthesis of stable nanotags with a series of protective coatings to provide stability in harsh environments and catalytic activity. The catalytic activity of the nanotags were assessed using TMB and ABTS in the presence of H2O2 and the most promising were used for the detection of biomolecules with Raman spectroscopy which provided low limits of detection and were carried out on portable instruments making infield detection possible. The catalytic activity of silver nanoparticles were also used in a surface based silverlinked immunosorbent assay to detect human C-reactive protein (CRP), an inflammatory marker and to detect oxidative stress in cancerous cells by monitoring the oxidation of TMB and analysing with SERRS. Overall, nanozymes and Raman spectroscopy detection can be applied to a variety of applications leading to lower limits of detection of biomolecules in harsh environments and a cheaper alternative to enzymes.Artificial enzymes have become an increasingly interesting area of research due to their many advantages over natural protein enzymes which are expensive, difficult to isolate and unable to stand harsh environments. An important area of this research involves using metal nanoparticles as artificial enzymes, known as nanozymes, which exhibit peroxidase-like activity enabling them to catalyse the oxidation of substrates such as 3,3',5,5'-tetramethylbenzidine (TMB) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) and in the presence of hydrogen peroxide (H2O2). This yields a colorimetric response which can be characterised using ultraviolet-visible (UV-vis) spectroscopy, Resonance Raman scattering (RRS) and surface enhanced resonance Raman scattering (SERRS). Nanozymes have been applied to various different applications, some of which are explored in this thesis. The overall aim of this research was to investigate the synthesis of stable nanotags with a series of protective coatings to provide stability in harsh environments and catalytic activity. The catalytic activity of the nanotags were assessed using TMB and ABTS in the presence of H2O2 and the most promising were used for the detection of biomolecules with Raman spectroscopy which provided low limits of detection and were carried out on portable instruments making infield detection possible. The catalytic activity of silver nanoparticles were also used in a surface based silverlinked immunosorbent assay to detect human C-reactive protein (CRP), an inflammatory marker and to detect oxidative stress in cancerous cells by monitoring the oxidation of TMB and analysing with SERRS. Overall, nanozymes and Raman spectroscopy detection can be applied to a variety of applications leading to lower limits of detection of biomolecules in harsh environments and a cheaper alternative to enzymes
Development and investigation of novel chemoselective processes in Pd and Cu catalysis
Get PDFThe development of chemoselective processes is of utmost importance for the future of synthetic organic chemistry, and has been described as 'the single greatest obstacle to complex molecule synthesis'. Chemoselectivity is required to exploit the full potential of synthetic developments in organic chemistry, allowing for more efficient procedures and better route design. This thesis will describe the development of chemoselective processes across two cornerstone reactions in organic chemistry. Chapter one will describe the development of dual nucleophile/electrophile chemoselectivity in the Suzuki-Miyaura reaction. Chemoselectivity in this key crosscoupling reaction has previously only been achieved at either the nucleophile or the electrophile independently. Electrophile chemoselectivity is generally well defined and has been used extensively in both academic and industrial settings. Chemoselectivity of the nucleophilic component has been less well explored, and has only been achieved through three distinct approaches; protecting group chemistries, vicinal/geminal activation, and aryl/benzyl selectivity that is based upon activating Ag additives. Herein, we describe the use of media controlled boron speciation between aryl/vinyl BPins and BMIDAs to realize the first example of dual nucleophile/electrophile chemoselectivity. The method was exemplified through the synthesis of a range of diverse substrates and a BET bromodomain inhibitor. Chapter two will describe an investigation into the source of rate independent chemoselectivity in the CuAAC reaction. Chemoselectivity in the CuAAC reaction has chiefly been demonstrated through the use of either activated or deactivated azides, whereas alkyne chemoselectivity is less well developed. Recent work from the Watson and Burley groups described the use of aromatic ynamines to afford exquisite chemoselectivity over alkyl alkynes, allowing for sequential functionalization of multifunctional bisalkynes. Herein, we describe the development of a reactivity scale for alkynes in the CuAAC reaction and a kinetic investigation into the origin of selectivity when using ynamine substrates. A chelation-assisted change in the rate-determining step from Cu-acetylide formation to azide ligation/insertion allows for chemoselectivity over more reactive alkynes despite a slower overall rate. This was harnessed to develop an orthogonal ligation strategy from protected ynamine substrates.The development of chemoselective processes is of utmost importance for the future of synthetic organic chemistry, and has been described as 'the single greatest obstacle to complex molecule synthesis'. Chemoselectivity is required to exploit the full potential of synthetic developments in organic chemistry, allowing for more efficient procedures and better route design. This thesis will describe the development of chemoselective processes across two cornerstone reactions in organic chemistry. Chapter one will describe the development of dual nucleophile/electrophile chemoselectivity in the Suzuki-Miyaura reaction. Chemoselectivity in this key crosscoupling reaction has previously only been achieved at either the nucleophile or the electrophile independently. Electrophile chemoselectivity is generally well defined and has been used extensively in both academic and industrial settings. Chemoselectivity of the nucleophilic component has been less well explored, and has only been achieved through three distinct approaches; protecting group chemistries, vicinal/geminal activation, and aryl/benzyl selectivity that is based upon activating Ag additives. Herein, we describe the use of media controlled boron speciation between aryl/vinyl BPins and BMIDAs to realize the first example of dual nucleophile/electrophile chemoselectivity. The method was exemplified through the synthesis of a range of diverse substrates and a BET bromodomain inhibitor. Chapter two will describe an investigation into the source of rate independent chemoselectivity in the CuAAC reaction. Chemoselectivity in the CuAAC reaction has chiefly been demonstrated through the use of either activated or deactivated azides, whereas alkyne chemoselectivity is less well developed. Recent work from the Watson and Burley groups described the use of aromatic ynamines to afford exquisite chemoselectivity over alkyl alkynes, allowing for sequential functionalization of multifunctional bisalkynes. Herein, we describe the development of a reactivity scale for alkynes in the CuAAC reaction and a kinetic investigation into the origin of selectivity when using ynamine substrates. A chelation-assisted change in the rate-determining step from Cu-acetylide formation to azide ligation/insertion allows for chemoselectivity over more reactive alkynes despite a slower overall rate. This was harnessed to develop an orthogonal ligation strategy from protected ynamine substrates
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