44 resultados para Direct effect

em Aston University Research Archive


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The effect of friction and interparticle cohesion forces on the gas-solid flow hydrodynamics was discussed. A proposed interparticle cohesion and frictional force terms have been tested in a continuum fully developed flow model to investigate their effect on the general hydrodynamic features of vertical duct flow. It was observed that both terms have direct effect on lowering the material carryover, which implies a reduced bed expansion in freely bubbling column. The parametric analysis shows that cohesion and frictional forces are high when compared to kinetic stress and hence it can play a major role in describing the hydrodynamics features of the flow.

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Monocyte recruitment and retention in the vasculature is influenced by oxidative stress and is involved in cardiovascular disease (CVD). Individuals with low plasma ascorbate are at elevated risk of CVD. It is unknown whether vitamin C supplementation affects monocyte adhesion to endothelial cells (ECs) in healthy non-smokers. In a randomised double-blind crossover study the effect of vitamin C supplementation (six weeks, 250 mg/day) was determined in subjects with normal (HIC) and below average (LOC) plasma vitamin C concentration at baseline (mean = 67μM, n = 20, mean = 32μM, n = 20, respectively). LOC subjects showed 30% greater monocyte adhesion to ECs. This was significantly reduced by 37% (P < 0.02) following vitamin C supplementation to levels of HIC monocyte adhesion. No differences in plasma malondialdehyde concentrations were observed between groups or after supplementation. In conclusion, vitamin C supplementation normalises monocyte adhesion in subjects with low plasma vitamin C (LOC). This process may be related to a direct effect on monocytes, independent of lipid peroxidation. © 2002 Elsevier Science (USA). All rights reserved.

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The procedure for successful scale-up of batchwise emulsion polymerisation has been studied. The relevant literature on liquid-liquid dispersion on scale-up and on emulsion polymerisation has been crit1cally reviewed. Batchwise emulsion polymerisation of styrene in a specially built 3 litre, unbaffled, reactor confirmed that impeller speed had a direct effect on the latex particle size and on the reaction rate. This was noted to be more significant at low soap concentrations and the phenomenon was related to the depletion of micelle forming soap by soap adsorption onto the monomer emulsion surface. The scale-up procedure necessary to maintain constant monomer emulsion surface area in an unbaffled batch reactor was therefore investigated. Three geometrically similar 'vessels of 152, 229 and 305mm internal diameter, and a range of impeller speeds (190 to 960 r.p.m.) were employed. The droplet sizes were measured either through photomicroscopy or via a Coulter Counter. The power input to the impeller was also measured. A scale-up procedure was proposed based on the governing relationship between droplet diameter, impeller speed and impeller diameter. The relationships between impeller speed soap concentration, latex particle size and reaction rate were investigated in a series of polymerisations employing an amended commercial recipe for polystyrene. The particle size was determined via a light transmission technique. Two computer models, based on the Smith and Ewart approach but taking into account the adsorption/desorption of soap at the monomer surface, were successful 1n predicting the particle size and the progress of the reaction up to the end of stage II, i.e. to the end of the period of constant reaction rate.

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Patients with cancer often undergo a specific loss of skeletal muscle mass, while the visceral protein reserves are preserved. This condition known as cachexia reduces the quality of life and eventually results in death through erosion of the respiratory muscles. Nutritional supplementation or appetite stimulants are unable to restore the loss of lean body mass, since protein catabolism is increased mainly as a result of the activation of the ATP-ubiquitin-dependent proteolytic pathway. Several mediators have been proposed. An enhanced protein degradation is seen in skeletal muscle of mice administered tumour necrosis factor (TNF), which appears to be mediated by oxidative stress. There is some evidence that this may be a direct effect and is associated with an increase in total cellular-ubiquitin-conjugated muscle proteins. Another cytokine, interleukin-6 (IL-6), may play a role in muscle wasting in certain animal tumours, possibly through both lysosomal (cathepsin) and non-lysosomal (proteasome) pathways. A tumour product, proteolysis-inducing factor (PIF) is produced by cachexia-inducing murine and human tumours and initiates muscle protein degradation directly through activation of the proteasome pathway. The action of PIF is blocked by eicosapentaenoic acid (EPA), which has been shown to attenuate the development of cachexia in pancreatic cancer patients. When combined with nutritional supplementation EPA leads to accumulation of lean body mass and prolongs survival. Further knowledge on the biochemical mechanisms of muscle protein catabolism will aid the development of effective therapy for cachexia.

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We present the first innovation value chain analysis for a representative sample of new technology based firms (NTBFs) in the UK. This involves determining which factors lead to the usage of different knowledge sources and the relationships that exist between those sources of knowledge; the effect that each knowledge source has on innovative activity; and how innovation outputs affect the performance of NTBFs. We find that internal and external knowledge sources are complementary for NTBFs, and that supply chain linkages have both a direct and indirect effect on innovation. NTBFs’ skill resources matter throughout the innovation value chain, being positively associated with external knowledge linkages and innovation success, and also having a direct effect on growth independent of the effect on innovation. Exporting matters for performance, but not through any effect on innovation.

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This study examines the effect of budgetary participation on departmental performance via budget adequacy, organisational commitment and role ambiguity. The responses of 108 budget preparers and budget users drawn from a cross-section of Malaysian local authorities, to a questionnaire survey were analysed by using mediation analysis, path analysis and Pearson Product-Moment Correlation technique. The results suggest that budget adequacy, organisational commitment, and role ambiguity are important links in the process. The results of this study suggest that the relationship between budget participation and departmental performance is statistically, significantly, positively and marginally correlated. Of more interest was the finding that budget adequacy, organisational commitment, and role ambiguity are important intervening variables in the relationship between budget participation and departmental performance. The test for mediation effect, demonstrated that budget adequacy, organisational commitment, and role ambiguity had partially mediated the relationship of budget participation and departmental performance. These three variables act as partial mediators when they significantly reduced or decreased the path coefficient of budget participation and departmental performance rather than eliminating the relationship. Furthermore, the test for direct and indirect effect of budget participation on departmental performance, suggests that budget participation predicted or affected departmental performance more strongly in the indirect way than it did in a direct way. This suggests that, even though the correlation between budget participation and departmental performance was significant, the path interpretation suggests that the correlation arose because budget participation was correlated with other variables that have direct effect upon departmental performance not budget participation itself directly predicted departmental performance. Therefore, there is enough evidence to suggest that budget participation of budget preparers and budget users affects departmental performance of Malaysian local authorities indirectly via budget adequacy, organisational commitment and role ambiguity. Among the indirect effects, the link between budget participation, budget adequacy, organisational commitment, role ambiguity and departmental performance may be the most important in term of this study’s contribution. The decomposition of the observed correlation between budget participation, budget adequacy, organisational commitment and role ambiguity showed that budget 3 participation of budget preparers and budget users of Malaysian local authorities in the budget setting has direct effect on budget adequacy, organisational commitment and role ambiguity. Budget adequacy and organisational commitment was directly related. However, the relationship of role ambiguity and organisational commitment in this study was indirectly related. This suggests that participation of budget preparers and budget users in the budget setting of Malaysian local authorities lead to decrease role ambiguity that provide adequate budgetary supports, which lead to increase organisational commitment and thus enhance departmental performance. In relation to the strength of the relationships of the variables undertaken for the study, the overall relationships between variables are significant and positively related except that of role ambiguity relationship. The relationships of role ambiguity with budget participation, budget adequacy, organisational performance and departmental performance are negatively related.

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Increased awareness of the crucial role of leadership as a competitive advantage for organisations (McCall, 1998; Petrick, Scherer, Brodzinski, Quinn, & Ainina, 1999) has led to billions spent on leadership development programmes and training (Avolio & Hannah, 2008). However, research reports confusing and contradictory evidence regarding return on investment and developmental outcomes, and a lot of variance has been observed across studies (Avolio, Reichard, Hannah, Walumbwa, & Chan, 2009). The purpose of this thesis is to understand the mechanisms underlying this variability in leadership development. Of the many factors at play in the process, such as programme design and delivery, organisational support, and perceptions of relevance (Mabey, 2002; Day, Harrison, & Halpin, 2009), individual differences and characteristics stand out. One way in which individuals differ is in their Developmental Readiness (DR), a concept recently introduced in the literature that may well explain this variance and which has been proposed to accelerate development (Avolio & Hannah, 2008, 2009). Building on previous work, DR is introduced and conceptualised somewhat differently. In this study, DR is construed of self-awareness, self-regulation, and self-motivation, proposed by Day (2000) to be the backbones of leadership development. DR is suggested to moderate the developmental process. Furthermore, personality dispositions and individual values are proposed to be precursors of DR. The empirical research conducted uses a pre-test post-test quasi-experimental design. Before conducting the study, though, both a measure of Developmental Readiness and a competency profiling measure are tested in two pilot studies. Results do not find evidence of a direct effect of leadership development programmes on development, but do support an interactive effect between DR and leadership development programmes. Personality dispositions Agreeableness, Conscientiousness, and Openness to Experience and value orientations Conservation, Open, and Closed Orientation are found to significantly predict DR. Finally, the theoretical and practical implications of findings are discussed.

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Customer satisfaction and service quality are two important concepts in the marketing literature. However, there has been some confusion about the conceptualisation and measurement of these two concepts and the nature of the relationship between them. The primary objective of this research was to develop a more thorough understanding of these concepts, and a model that could help to explain the links between them and their relationships with post-purchase behaviour. A preliminary theoretical model was developed, based on an exhaustive review of the literature. Following exploratory research, the model was revised by incorporating "Perceived Value" and "Perceived Sacrifice" to help explain customer's post-purchase behaviour. A longitudinal survey was conducted in the context of the restaurant industry, and the data were analysed using structural equation modelling. The results provided evidence to support the main research hypotheses. However, the effect of "Normative Expectations" on "Encounter Quality" was insignificant, and "Perceived Value" had a direct effect on "Behavioural Intentions" despite expectations that such an effect would be mediated through "Customer Satisfaction". It was also found that "Normative Expectations" were relatively more stable than "Predictive Expectations". It is argued that the present research significantly contributes to the marketing literature, and in particular the role of perceived value in the formation of customers' post-purchase behaviour. Further research efforts in this area are warranted.

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New Technology Based Firms (NTBF) are considered to be important for the economic development of a country in regards to both employment growth and innovative activity. The latter is believed to contribute significantly to the increase in productivity and therefore the competitiveness of UK’s economy. This study contributes to the above literature by investigating two of the factors believed to limit the growth of such firms in the UK. The first concerns the existence of a ‘knowledge gap’ while the second the existence of a ‘financial gap’. These themes are developed along three main research lines. Firstly, based upon the human capital theory initially proposed by Backer (1964) new evidence is provided on the human capital characteristics (experience and education) of the current UK NTBF entrepreneurs. Secondly, the causal relationship between general and specific human capital (as well as their interactions) upon the company performance and growth is investigated via its traditional direct effect as well as via its indirect effect upon the access to external finance. Finally, more light is shed on the financial structure and the type of financial constraints that high-tech firms face at start-up. In particular, whether a financial gap exists is explored by distinguishing between the demand and the supply of external finance as well as by type of external source of financing. The empirical testing of the various research hypotheses has been obtained by carrying out an original survey of new technology based firms defined as independent companies, established in the past 25 years in R&D intensive sectors. The resulting dataset contains information for 412 companies on a number of general company characteristics and the characteristics of their entrepreneurs in 2004. Policy and practical implications for future and current entrepreneurs and also providers of external finance are provided.

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This article investigates whether (1) cross-functional integration within a firm and the use of information systems (IS) that support information sharing with external parties can enhance integration across the supply chain and wider networks and (2) whether collaboration with customers, suppliers and other external parties leads to increased supply chain performance in terms of new product development and introduction of new processes. Data from a high-quality survey carried out in Taiwan in 2009 were used, and appropriate econometric models were applied. Results show that the adoption of IS that enhance information sharing is vital not only for the effective communication with suppliers and with wider network members, but their adoption also has a direct effect across a firm's innovative effort. Cross-functional integration appears to matter only for the introduction of an innovative process. Collaboration with customers and suppliers affected a product's design and its overall features and functionality, respectively. © 2013 Copyright Taylor and Francis Group, LLC.

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Early embryonic development is known to be susceptible to maternal undernutrition, leading to a disease-related postnatal phenotype. To determine whether this sensitivity extended into oocyte development, we examined the effect of maternal normal protein diet (18% casein; NPD) or isocaloric low protein diet (9% casein; LPD) restricted to one ovulatory cycle (3.5 days) prior to natural mating in female MF-1 mice. After mating, all females received NPD for the remainder of gestation and all offspring were litter size adjusted and fed standard chow. No difference in gestation length, litter size, sex ratio or postnatal growth was observed between treatments. Maternal LPD did, however, induce abnormal anxiety-related behaviour in open field activities in male and female offspring (P <0.05). Maternal LPD offspring also exhibited elevated systolic blood pressure (SBP) in males at 9 and 15 weeks and in both sexes at 21 weeks (P <0.05). Male LPD offspring hypertension was accompanied by attenuated arterial responsiveness in vitro to vasodilators acetylcholine and isoprenaline (P <0.05). LPD female offspring adult kidneys were also smaller, but had increased nephron numbers (P <0.05). Moreover, the relationship between SBP and kidney or heart size or nephron number was altered by diet treatment (P <0.05). These data demonstrate the sensitivity of mouse maturing oocytes in vivo to maternal protein undernutrition and identify both behavioural and cardiovascular postnatal outcomes, indicative of adult disease. These outcomes probably derive from a direct effect of protein restriction, although indirect stress mechanisms may also be contributory. Similar and distinct postnatal outcomes were observed here compared with maternal LPD treatment during post-fertilization preimplantation development which may reflect the relative contribution of the paternal genome. © Journal compilation © 2008 The Physiological Society.

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Previous research suggests that the attitudes and behaviours of front-line employees (FLEs) significantly influence customers’ evaluations of service quality and customer satisfaction. Therefore, it becomes important to identify the variables that influence FLEs job attitudes and Prosocial ServiceBehaviours (PSBs). The conceptual framework developed from extant literature is presented, which proposes that management interventions (internal communication, training and development and empowerment) have a direct effect on PSBs. In addition, these relationships are mediated by role stress and job attitudes. Implications for service management and future research directions are discussed.

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The focus of this study is on the governance decisions in a concurrent channels context, in the case of uncertainty. The study examines how a firm chooses to deploy its sales force in times of uncertainty, and the subsequent performance outcome of those deployment choices. The theoretical framework is based on multiple theories of governance, including transaction cost analysis (TCA), agency theory, and institutional economics. Three uncertainty variables are investigated in this study. The first two are demand and competitive uncertainty which are considered to be industry-level market uncertainty forms. The third uncertainty, political uncertainty, is chosen as it is an important dimension of institutional environments, capturing non-economic circumstances such as regulations and political systemic issues. The study employs longitudinal secondary data from a Thai hotel chain, comprising monthly observations from January 2007 – December 2012. This hotel chain has its operations in 4 countries, Thailand, the Philippines, United Arab Emirates – Dubai, and Egypt, all of which experienced substantial demand, competitive, and political uncertainty during the study period. This makes them ideal contexts for this study. Two econometric models, both deploying Newey-West estimations, are employed to test 13 hypotheses. The first model considers the relationship between uncertainty and governance. The second model is a version of Newey-West, using an Instrumental Variables (IV) estimator and a Two-Stage Least Squares model (2SLS), to test the direct effect of uncertainty on performance and the moderating effect of governance on the relationship between uncertainty and performance. The observed relationship between uncertainty and governance observed follows a core prediction of TCA; that vertical integration is the preferred choice of governance when uncertainty rises. As for the subsequent performance outcomes, the results corroborate that uncertainty has a negative effect on performance. Importantly, the findings show that becoming more vertically integrated cannot help moderate the effect of demand and competitive uncertainty, but can significantly moderate the effect of political uncertainty. These findings have significant theoretical and practical implications, and extend our knowledge of the impact on uncertainty significantly, as well as bringing an institutional perspective to TCA. Further, they offer managers novel insight into the nature of different types of uncertainty, their impact on performance, and how channel decisions can mitigate these impacts.

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We present an innovation value chain analysis for a representative sample of new technology based firms (NTBFs) in the UK. This involves determining which factors lead to the usage of different knowledge sources and the relationships that exist between those sources of knowledge; the effect that each knowledge source has on innovative activity; and how innovation outputs affect the performance of NTBFs. We find that internal (i.e. R&D) and external knowledge sources are complementary for NTBFs, and that supply chain linkages have both a direct and indirect effect on innovation. NTBFs' skill resources matter throughout the innovation value chain, being positively associated with external knowledge linkages and innovation success, and also having a direct effect on growth independent of the effect on innovation. ©2010 IEEE.

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We present an innovation value chain analysis for a representative sample of new technology based firms (NTBFs) in the UK. This involves determining which factors lead to the usage of different knowledge sources and the relationships that exist between those sources of knowledge; the effect that each knowledge source has on innovative activity; and how innovation outputs affect the performance of NTBFs. We find that internal (i.e. R&D) and external knowledge sources are complementary for NTBFs, and that supply chain linkages have both a direct and indirect effect on innovation. NTBFs' skill resources matter throughout the innovation value chain, being positively associated with external knowledge linkages and innovation success, and also having a direct effect on growth independent of the effect on innovation. ©2010 IEEE.