8 resultados para growth, development and aging
em Aston University Research Archive
Resumo:
Recent discussion of the knowledge-based economy draws increasingly attention to the role that the creation and management of knowledge plays in economic development. Development of human capital, the principal mechanism for knowledge creation and management, becomes a central issue for policy-makers and practitioners at the regional, as well as national, level. Facing competition both within and across nations, regional policy-makers view human capital development as a key to strengthening the positions of their economies in the global market. Against this background, the aim of this study is to go some way towards answering the question of whether, and how, investment in education and vocational training at regional level provides these territorial units with comparative advantages. The study reviews literature in economics and economic geography on economic growth (Chapter 2). In growth model literature, human capital has gained increased recognition as a key production factor along with physical capital and labour. Although leaving technical progress as an exogenous factor, neoclassical Solow-Swan models have improved their estimates through the inclusion of human capital. In contrast, endogenous growth models place investment in research at centre stage in accounting for technical progress. As a result, they often focus upon research workers, who embody high-order human capital, as a key variable in their framework. An issue of discussion is how human capital facilitates economic growth: is it the level of its stock or its accumulation that influences the rate of growth? In addition, these economic models are criticised in economic geography literature for their failure to consider spatial aspects of economic development, and particularly for their lack of attention to tacit knowledge and urban environments that facilitate the exchange of such knowledge. Our empirical analysis of European regions (Chapter 3) shows that investment by individuals in human capital formation has distinct patterns. Those regions with a higher level of investment in tertiary education tend to have a larger concentration of information and communication technology (ICT) sectors (including provision of ICT services and manufacture of ICT devices and equipment) and research functions. Not surprisingly, regions with major metropolitan areas where higher education institutions are located show a high enrolment rate for tertiary education, suggesting a possible link to the demand from high-order corporate functions located there. Furthermore, the rate of human capital development (at the level of vocational type of upper secondary education) appears to have significant association with the level of entrepreneurship in emerging industries such as ICT-related services and ICT manufacturing, whereas such association is not found with traditional manufacturing industries. In general, a high level of investment by individuals in tertiary education is found in those regions that accommodate high-tech industries and high-order corporate functions such as research and development (R&D). These functions are supported through the urban infrastructure and public science base, facilitating exchange of tacit knowledge. They also enjoy a low unemployment rate. However, the existing stock of human and physical capital in those regions with a high level of urban infrastructure does not lead to a high rate of economic growth. Our empirical analysis demonstrates that the rate of economic growth is determined by the accumulation of human and physical capital, not by level of their existing stocks. We found no significant effects of scale that would favour those regions with a larger stock of human capital. The primary policy implication of our study is that, in order to facilitate economic growth, education and training need to supply human capital at a faster pace than simply replenishing it as it disappears from the labour market. Given the significant impact of high-order human capital (such as business R&D staff in our case study) as well as the increasingly fast pace of technological change that makes human capital obsolete, a concerted effort needs to be made to facilitate its continuous development.
Resumo:
The development of new areolae on the marginal hypothallus of the lichen Rhizocarpon geographicum (L.) DC was studied after complete or partial removal of the central areolae. New areolae developed slowly on the isolated hypothalli over two years. Development was similar when the areolae were completely removed and when the central areolae were separated from the marginal hypothallus by ‘moats’ 2 to 5 mm in width. However, in intact thalli, the marginal areolae developed rapidly during Jan. – June 1986 but showed periods of retreat from the margin during Oct. - Dec. 1985 and July – Sept. 1986. These results suggested that primary areolae may develop from free-living algal cells trapped by the hypothallus while secondary areolae may develop from zoospores produced by the thallus. Complete removal of the areolae resulted in no measurable radial growth of the marginal hypothallus over 18 months. Removal of the central areolae to within 1 and 2 mm of the hypothallus significantly reduced growth. These results suggest that the areolae may supply the hypothallus with carbon for growth. When the marginal hypothallus was experimentally removed a new hypothallus developed within one year. Regeneration occurred initially by retreat of the marginal areolae and later by new hyphal growth. The concentration of ribitol, arabitol and mannitol was measured in the areolae and marginal hypothallus on four occasions in 1985/6 in a population growing on a steep south facing rock surface. The three carbohydrates were present in significantly higher concentration in the areolae than in the hypothallus. Hence, the slow growth of this species may result from inhibited transport of carbohydrate from areolae to hypothallus.
Resumo:
A nonlinear dynamic model of microbial growth is established based on the theories of the diffusion response of thermodynamics and the chemotactic response of biology. Except for the two traditional variables, i.e. the density of bacteria and the concentration of attractant, the pH value, a crucial influencing factor to the microbial growth, is also considered in this model. The pH effect on the microbial growth is taken as a Gaussian function G0e-(f- fc)2/G1, where G0, G1 and fc are constants, f represents the pH value and fc represents the critical pH value that best fits for microbial growth. To study the effects of the reproduction rate of the bacteria and the pH value on the stability of the system, three parameters a, G0 and G1 are studied in detail, where a denotes the reproduction rate of the bacteria, G0 denotes the impacting intensity of the pH value to microbial growth and G1 denotes the bacterial adaptability to the pH value. When the effect of the pH value of the solution which microorganisms live in is ignored in the governing equations of the model, the microbial system is more stable with larger a. When the effect of the bacterial chemotaxis is ignored, the microbial system is more stable with the larger G1 and more unstable with the larger G0 for f0 > fc. However, the stability of the microbial system is almost unaffected by the variation G0 and G1 and it is always stable for f0 < fc under the assumed conditions in this paper. In the whole system model, it is more unstable with larger G1 and more stable with larger G0 for f0 < fc. The system is more stable with larger G1 and more unstable with larger G0 for f0 > fc. However, the system is more unstable with larger a for f0 < fc and the stability of the system is almost unaffected by a for f0 > fc. The results obtained in this study provide a biophysical insight into the understanding of the growth and stability behavior of microorganisms.
Resumo:
Human and animal studies have revealed a strong association between periconceptional environmental factors, such as poor maternal diet, and an increased propensity for cardiovascular and metabolic disease in adult offspring. Previously, we reported cardiovascular and physiological effects of maternal low protein diet (LPD) fed during discrete periods of periconceptional development on 6-month-old mouse offspring. Here, we extend the analysis in 1 year aging offspring, evaluating mechanisms regulating growth and adiposity. Isocaloric LPD (9% casein) or normal protein diet (18% casein; NPD) was fed to female MF-1 mice either exclusively during oocyte maturation (for 3.5 days prior to mating; Egg-LPD, Egg-NPD, respectively), throughout gestation (LPD, NPD) or exclusively during preimplantation development (for 3.5 days post mating; Emb-LPD). LPD and Emb-LPD female offspring were significantly lighter and heavier than NPD females respectively for up to 52 weeks. Egg-LPD, LPD and Emb-LPD offspring displayed significantly elevated systolic blood pressure at 52 weeks compared to respective controls (Egg-NPD, NPD). LPD females had significantly reduced inguinal and retroperitoneal fat pad: body weight ratios compared to NPD females. Expression of the insulin receptor (Insr) and insulin-like growth factor I receptor (Igf1r) in retroperitoneal fat was significantly elevated in Emb-LPD females (P&0.05), whilst Emb-LPD males displayed significantly decreased expression of the mitochondrial uncoupling protein 1 (Ucp1) gene compared to NPD offspring. LPD females displayed significantly increased expression of Ucp1 in interscapular brown adipose tissue when compared to NPD offspring. Our results demonstrate that aging offspring body weight, cardiovascular and adiposity homeostasis can be programmed by maternal periconceptional nutrition. These adverse outcomes further exemplify the criticality of dietary behaviour around the time of conception on long-term offspring health. © 2011 Watkins et al.
Resumo:
Retinoic acid (RA) signaling is important to normal development. However, the function of the different RA receptors (RARs)-RARα, RARβ, and RARγ-is as yet unclear. We have used wild-type and transgenic zebrafish to examine the role of RARγ. Treatment of zebrafish embryos with an RARγ-specific agonist reduced somite formation and axial length, which was associated with a loss of hoxb13a expression and less-clear alterations in hoxc11a or myoD expression. Treatment with the RARγ agonist also disrupted formation of tissues arising from cranial neural crest, including cranial bones and anterior neural ganglia. There was a loss of Sox 9-immunopositive neural crest stem/progenitor cells in the same anterior regions. Pectoral fin outgrowth was blocked by RARγ agonist treatment. However, there was no loss of Tbx-5-immunopositive lateral plate mesodermal stem/progenitor cells and the block was reversed by agonist washout or by cotreatment with an RARγ antagonist. Regeneration of the caudal fin was also blocked by RARγ agonist treatment, which was associated with a loss of canonical Wnt signaling. This regenerative response was restored by agonist washout or cotreatment with the RARγ antagonist. These findings suggest that RARγ plays an essential role in maintaining stem/progenitor cells during embryonic development and tissue regeneration when the receptor is in its nonligated state.
Resumo:
The object of this work was to further develop the idea introduced by Muaddi et al (1981) which enables some of the disadvantages of earlier destructive adhesion test methods to be overcome. The test is non-destructive in nature but it does need to be calibrated against a destructive method. Adhesion is determined by measuring the effect of plating on internal friction. This is achieved by determining the damping of vibrations of a resonating specimen before and after plating. The level of adhesion was considered by the above authors to influence the degree of damping. In the major portion of the research work the electrodeposited metal was Watt's nickel, which is ductile in nature and is therefore suitable for peel adhesion testing. The base metals chosen were aluminium alloys S1C and HE9 as it is relatively easy to produce varying levels of adhesion between the substrate and electrodeposited coating by choosing the appropriate process sequence. S1C alloy is the commercially pure aluminium and was used to produce good adhesion. HE9 aluminium alloy is a more difficult to plate alloy and was chosen to produce poorer adhesion. The "Modal Testing" method used for studying vibrations was investigated as a possible means of evaluating adhesion but was not successful and so research was concentrated on the "Q" meter. The method based on the use of a "Q" meter involves the principle of exciting vibrations in a sample, interrupting the driving signal and counting the number of oscillations of the freely decaying vibrations between two known preselected amplitudes of oscillations. It was not possible to reconstruct a working instrument using Muaddi's thesis (1982) as it had either a serious error or the information was incomplete. Hence a modified "Q" meter had to be designed and constructed but it was then difficult to resonate non-magnetic materials, such as aluminium, therefore, a comparison before and after plating could not be made. A new "Q" meter was then developed based on an Impulse Technique. A regulated miniature hammer was used to excite the test piece at the fundamental mode instead of an electronic hammer and test pieces were supported at the two predetermined nodal points using nylon threads. This instrument developed was not very successful at detecting changes due to good and poor pretreatments given before plating, however, it was more sensitive to changes at the surface such as room temperature oxidation. Statistical analysis of test results from untreated aluminium alloys show that the instrument is not always consistent, the variation was even bigger when readings were taken on different days. Although aluminium is said to form protective oxides at room temperature there was evidence that the aluminium surface changes continuously due to film formation, growth and breakdown. Nickel plated and zinc alloy immersion coated samples also showed variation in Q with time. In order to prove that the variations in Q were mainly due to surface oxidation, aluminium samples were lacquered and anodised Such treatments enveloped the active surfaces reacting with the environment and the Q variation with time was almost eliminated especially after hard anodising. This instrument detected major differences between different untreated aluminium substrates.Also Q values decreased progressively as coating thicknesses were increased. This instrument was also able to detect changes in Q due to heat-treatment of aluminium alloys.
Resumo:
This thesis describes the history of robots and explains the reasons for the international differences in robot diffusion, and the differences in the diffusion of various robot applications with reference to the UK. As opposed to most of the literature, diffusion is examined with an integrated and interdisciplinary perspective. Robot technology evolves from the interaction of development, supply and manufacture, adoption, and promotion. activities. Emphasis is given to the analysis of adoption, at present the most important limiting factor of robot advancement in the UK. Technical development is inferred from a comparison of surveys on equipment, and from the topics of ten years of symposia papers. This classification of papers is also used to highlight the international and institutional differences in robot development. Analysis of the growth in robot supply, manufacture, and use is made from statistics compiled. A series of interviews with users and potential users serves to illustrate the factors and implications of the adoption of different robot systems in the UK. Adoption pioneering takes place when several conditions exist: when the technology is compatible with the firm, when its advantages outweigh its disadvantages, and particularly when a climate exists which encourages the managerial involvement and the labour acceptance. The degree of compatibility (technical, methodological, organisational, and economic) and the consequences (profitability, labour impacts, and managerial effects) of different robot systems (transfer, manipulative, processing, and assembly) are determined by various aspects of manufacturing operations (complexity, automation, integration, labour tasks, and working conditions). The climate for adoption pioneering is basically determined by the performance of firms. The firms' policies on capital investment have as decisive a role in determining the profitability of robots as their total labour costs. The performance of the motor car industry and its machine builders explains, more than any other factor, the present state of robot advancement in the UK.
Resumo:
Rhizocarpon geographicum (L.) DC. is one of the most widely distributed species of crustose lichens. This unusual organism comprises yellow-green ‘areolae’ that contain the algal symbiont which develop and grow on the surface of a non-lichenized, fungal ‘hypothallus’ that extends beyond the margin of the areolae to form a marginal ring. This species grows exceptionally slowly with annual radial growth rates (RGR) as low as 0.07 mm yr-1 and its considerable longevity has been exploited by geologists in the development of methods of dating the age of exposure of rock surfaces and glacial moraines (‘lichenometry’). Recent research has established some aspects of the basic biology of this important and interesting organism. This chapter describes the general structure of R. geographicum, how the areolae and hypothallus develop, why the lichen grows so slowly, the growth rate-size curve, and some aspects of the ecology of R. geographicum including whether the lichen can inhibit the growth of its neighbours by chemical means (‘allelopathy’). Finally, the importance of R. geographicum in direct and indirect lichenometry is reviewed.