7 resultados para Vine decline
em Aston University Research Archive
Resumo:
We studied the relationship between the decline in sensitivity that occurs with eccentricity for stimuli of different spatial scale defined by either luminance (LM) or contrast (CM) modulation. We show that the detectability of CM stimuli declines with eccentricity in a spatial frequency-dependent manner, and that the rate of sensitivity decline for CM stimuli is roughly that expected from their 1st order carriers, except, possibly, at finer scales. Using an equivalent noise paradigm, we investigated the possible reasons for why the foveal sensitivity for detecting LM and CM stimuli differs as well as the reason why the detectability of 1st order stimuli declines with eccentricity. We show the former can be modeled by an increase in internal noise whereas the latter involves both an increase in internal noise and a loss of efficiency. To encompass both the threshold and suprathreshold transfer properties of peripheral vision, we propose a model in terms of the contrast gain of the underlying mechanisms.
Resumo:
Introduction Mild cognitive impairment (MCI) is a term used to describe a level of decline in cognition which is seen as an intermediate stage between normal ageing and dementia, and which many consider to be a prodromal stage of neurodegeneration that may become dementia. That is, it is perceived as a high risk level of cognitive change. The increasing burden of dementia in our society, but also our increasing understanding of its risk factors and potential interventions, require diligent management of MCI in order to find strategies that produce effective prevention of dementia. Aim To update knowledge regarding mild cognitive impairment, and to bring together and appraise evidence about the main features of clinical interest: definitions, prevalence and stability, risk factors, screening, and management and intervention. Methods Literature review and consensus of expert opinion. Results and conclusion MCI describes a level of impairment in which deteriorating cognitive functions still allow for reasonable independent living, including some compensatory strategies. While there is evidence for some early risk factors, there is still a need to more precisely delineate and distinguish early manifestations of frank dementia from cognitive impairment that is less likely to progress to dementia, and furthermore to develop improved prospective evidence for positive response to intervention. An important limitation derives from the scarcity of studies that take MCI as an endpoint. Strategies for effective management suffer from the same limitation, since most studies have focused on dementia. Behavioural changes may represent the most cost-effective approach.
Resumo:
The oxidoreductase Trx-1 (thioredoxin 1) is highly conserved and found intra- and extra-cellularly in mammalian systems. There is increasing interest in its capacity to regulate immune function based on observations of altered distribution and expression during ageing and disease. We have investigated previously whether extracellular T-cell or peripheral blood mononuclear cell Trx-1 levels serve as a robust marker of ageing. In a preliminary study of healthy older adults compared with younger adults, we showed that therewas a significant, butweak, relationshipwith age. Interestingly, patientswith rheumatoid arthritis and cancer have been described by others to secrete or express greater surface Trx-1 than predicted. It is interesting to speculate whether a decline in Trx-1 during ageing protects against such conditions, but correspondingly increases risk of disease associated with Trx-1 depletion such as cardiovascular disease. These hypotheses are being explored in the MARK-AGE study, and preliminary findings confirm an inverse correlation of surface Trx-1 with age. We review recent concepts around the role of Trx-1 and its partners in T-cell function on the cell surface and as an extracellular regulator of redox state in a secreted form. Further studies on the redox state and binding partners of surface and secreted Trx-1 in larger patient datasets are needed to improve our understanding of why Trx-1 is important for lifespan and immune function. © The Authors Journal compilation © 2014 Biochemical Society.
Resumo:
Purpose: This research paper aims to examine the global trends in publishing in the leading marketing journals between 1964 and 2008, focusing on how public policy intervention in the assessment and funding of academic research has influenced Britain's relative productivity in the world's leading marketing journals. Design/methodology/approach: The method was an audit of contributions to the leading journals based on the authors' affiliation, country of origin and country in which they obtained their doctoral training. Findings: The results show that the proportion of leading marketing publications by authors affiliated to British universities have held steady at about 2 per cent, while the productivity of several other countries has accelerated past Britain. However, to retain that share, Britain has increasingly depended upon importing people whose PhD is not British. This contrasts with some other European countries that are now more productive than Britain, but mainly recruit locals with local PhDs. The pattern of decline in the UK is related to the impact of Britain's research assessment exercise and the continuation of relatively weak social science research training. Research limitations/implications: The analysis is limited by only looking at one academic discipline and only the top few academic journals in the field. Practical implications: The findings have implications at several levels. At a national policy level it questions the value of the research assessment exercises that appear to have presided over a decline in research productivity. For institutions, it questions the value in investing in developing local talent when success has come to those who buy talent internationally. Perhaps, the major implication arises from Britain's academic productivity declining while neighbouring countries have grown in international excellence. Originality/value: At a time when the continuation of expensive university research assessments is being questioned the research findings add value to the current debate in showing how that very process has accompanied academic decline. © Emerald Group Publishing Limited.