In recent years, interest in nostalgia and its many potential benefits has blossomed, yet the nature of nostalgia in older adulthood has remained largely unexplored. This is surprising, given that nostalgia serves many functions which are highly relevant to older adults and which could determine whether they adjust poorly or well to older adulthood. In order to address this shortfall, this thesis reports on research exploring nostalgia and wellbeing across the lifespan. First, I compare the content of nostalgic and ordinary autobiographical memories using multiple coding methods. Results highlight the strong social orientation of nostalgia in older adults (Chapter 2). Second, I examine psychological wellbeing across the lifespan and demonstrate that stability or gains in wellbeing are contingent on nostalgia (Chapter 3). Furthermore, these age-related differences in psychological wellbeing are at least partly driven by a perception of limited time (Chapter 4). Finally, I explore whether there are individual differences in those who stand to benefit most from nostalgia. Results suggest that nostalgia may not meet the affiliative needs of high growth adults as they get older. This is demonstrated across a wide variety of measures, including psychological wellbeing (Chapter 5), subjective wellbeing and health (Chapter 6). Overall, this thesis emphasises the value of taking a lifespan perspective on nostalgia.

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This thesis is based in two parallel strands of research. The first is an exploration of the theoretical distinctions between two competing paradigms dominant in sexual health research: social cognition models and discourse theory. The second is an exploration of the practical use of a discourse theoretical approach to research accounts from people in the forty-something' age bracket about their experience of developing new sexually intimate relationships. Some developments in connectionist theory are used to explore some possible distinctions between implicit and explicit knowledge. These distinctions are then used to explore the scope of the two paradigms and, drawing on findings from the practical research, to discuss some implications for sexual health research and intervention.

Mindfulness derives from meditative traditions and is a form of mental training that is increasingly incorporated into Western treatment approaches for common mental health problems. This thesis addresses the prophylactic effects of mindfulness practice and the implications for the treatment of anxiety. The first paper considers the role of attention as a predominant mechanism of mindfulness. The paper reviews the evidence for the effects of mindfulness on attentional subsets and suggests that mindfulness may in part exert its benefits by ameliorating maladaptive attentional processes that have been implicated in the aetiology of anxiety. The empirical paper reports the results of a randomised controlled trial that directly compared the prophylactic and differential effects of two mindfulness practices on pharmacologically-induced state anxiety and negative affect through inhalation of 7.5% carbon dioxide (CO2). 60 participants engaged in 10 minutes of focused mindfulness, open mindfulness or relaxation prior to a 20-minute inhalation of 7.5% CO2 or air. Consistent with the evidence-base, this study found that mindfulness reduced self-reported state anxiety and negative affect significantly more so than a period of relaxation. In the context of non-significant reductions in autonomic measures of arousal, these findings support that mindfulness exerts its benefits through specific rather than non-specific effects. The results are consistent with contemporary conceptualisations of mindfulness mechanisms that highlight the key role of attention and suggest that clinical effects are exerted through top-down control mechanisms that support emotion regulation.

Objective: There is a general agreement that physical activity (PA) has a beneficial effect on health and those who are more active have a reduced risk of developing many chronic diseases, such as coronary heart disease (CHD). However, the amount, type and intensity of PA deemed to be sufficient to achieve good health remains unclear. Different methods have been used to categorise activity behaviour, but the level of agreement, consistency and coherence between methods and how this might influence their relationship with CHD risk factors and estimated CHD (eCHD) risk are poorly understood. This uncertainty is reflected in many different messages communicated to the public as to how active they should be to prevent chronic diseases. The primary objective of this thesis was to determine whether the methods used to categorise PA (as either inactive/active or level of PA) influence the extent to which PA is associated with CHD risk factors and eCHD risk. Methods: This thesis was divided into two parts. The first part was to conduct a secondary analysis of data on activity and CHD risk factors (blood pressure and lipid profile) obtained from the 2004 UK National Diet and Nutrition Survey (NDNS) in 1658 adults aged 19-64 years. Using the information obtained from the NDNS 7-day diary, it was possible to extend the original observations and to re-categorise individuals according to measures of PA in terms of number of days and minutes of at least moderate PA, total activity expressed as metabolic-equivalents (METs) and self-perception of PA. Each of these methods was then used to examine the proportion of the variance in CHD risk factors and the eCHD risk attributable to differences in PA using General Linear Modelling with adjustment for BMI, age and smoking. Partial eta squared a “proportion of variance due to physical activity plus error that is attributed to physical activity alone” was used. In the second part, the concurrent validity of measures of PA derived from the NDNS 7-day diary, using different systems for coding and classifying of different physical activities, was compared against those measures of PA obtained from the International Physical Activity Questionnaire (IPAQ) in a group of medical students (n = 26). Results: Taken together, this thesis revealed: 1) poor agreement across different methods of categorisation of PA level, 2) no support to justify a curvilinear dose-response relationship between PA level and CHD risk factors and eCHD risk and that a linear model was sufficient, 3) the differences in CHD risk factors or eCHD risk that could be directly attributable to differences in PA in men was modest (generally < 5%) although no associations evident in the women, 4) effect was most obviously demonstrable as improvements in lipid profile, no demonstrable effect on blood pressure, 5) a potential problem might arise when using one system and applying its results to different guidelines established by different systems. Conclusion: These findings support the view that being physically active is associated with markers of better health and lower CHD risk; a small but consistent effect that was the same irrespective of which method of categorizing PA was used and even after adjustment for differences in age, BMI and smoking. The effects were most evident in men and largely attributable to improvements in lipid metabolism.

Operating theatres and surgeons are among the most expensive resources in any hospital, so it is vital that they are used efficiently. Due to the complexity of the challenges involved in theatre scheduling we split the problem into levels and address the tactical and day-to-day scheduling problems. Cognitive mapping is used to identify the important factors to consider in theatre scheduling and their interactions. This allows development and testing of our understanding with hospital staff, ensuring that the aspects of theatre scheduling they consider important are included in the quantitative modelling. At the tactical level, our model assists hospitals in creating new theatre timetables, which take account of reducing the maximum number of beds required, surgeons’ preferences, surgeons’ availability, variations in types of theatre and their suitability for different types of surgery, limited equipment availability and varying the length of the cycle over which the timetable is repeated. The weightings given to each of these factors can be varied allowing exploration of possible timetables. At the day-to-day scheduling level we focus on the advanced booking of individual patients for surgery. Using simulation a range of algorithms for booking patients are explored, with the algorithms derived from a mixture of scheduling literature and ideas from hospital staff. The most significant result is that more efficient schedules can be achieved by delaying scheduling as close to the time of surgery as possible, however, this must be balanced with the need to give patients adequate warning to make arrangements to attend hospital for their surgery. The different stages of this project present different challenges and constraints, therefore requiring different methodologies. As a whole this thesis demonstrates that a range of methodologies can be applied to different stages of a problem to develop better solutions.

No description available.

Bacteria such as Escherichia coli and Salmonella are capable of causing gastrointestinal illness if ingested with food. There is an urgent need within the food processing industry to improve the efficiency of both the sanitising processes used on fresh produce and the microbiological methods used to ensure its safety. The aims of this study were to develop novel microscopic methods to detect and quantify both indigenous leaf bacteria and viable human pathogens on salad leaves, without the need for recovery and culture, which may reduce the accuracy of quantification. The methods developed could then be used to quantify the number of indigenous and inoculated bacteria in situ on salad leaves as well as to identify factors affecting the quantity and spatial patterning of attachment. In addition, the efficacy of chemical biocides for the reduction of viable Salmonella on salad leaves was considered. Episcopic Differential Interference Contrast (EDIC) microscopy coupled with epifluorescence was used to rapidly and non-destructively view the natural microflora in situ on spinach leaves. Salmonella enterica serovar Thompson was inoculated onto spinach leaves in order to observe spatial and temporal patterning of colonisation under differing conditions. Salmonella enterica serovar Typhimurium mutants defective in curli fimbriae production were used to assess the role of curli in attachment to abiotic surfaces and leaves. Viability determination of potential viable but non-culturable (VNC), sub-lethally stressed cells was performed to assess the effect of chemical wash treatments on Salmonella attached to fresh spinach. The results obtained indicate that salad leaves are densely populated with naturally occurring bacteria; these are found predominantly in the margins between leaf epidermal cells as well as around leaf veins and stomata. Cells were present in complex three-dimensional aggregations, suggesting the presence of biofilms. Curli fimbriae were shown to be key in the attachment of Salmonella typhimurium to polystyrene but not to leaf surfaces. When Salmonella thompson was inoculated onto spinach leaves and then subjected to chemical washing in chlorine or Citrox, neither chemical was an effective biocide against the pathogen. Under-reporting of viable cell numbers by plate counting methods indicated that chlorine induced a viable but nonculturable (VNC) state amongst Salmonella. These findings have important implications for the sanitisation of salads; both stomatal penetration and the formation of biofilms could protect enteric bacteria on leaves from chemical and mechanical disinfection strategies. If human pathogens are able to spread to salad leaves from contaminated soil, irrigation water or directly from animal faeces, and actively penetrate the interior of the leaves, then the microbiological safety of ready-to-eat salads cannot be guaranteed. This study also suggests that current methods for detection of pathogenic bacteria in foods following processing may be under-reporting the threat to consumers due to the induction of the VNC state amongst pathogenic bacteria.

A number of large scale Salmonella outbreaks have been associated with low aw food products where the significant causal factor was most likely cross-contamination. These studies sought to both: assess Salmonella survival and survival mechanisms when dried onto stainless steel under simulated food factory conditions, and to develop enhanced factory control approaches for this pathogen. Fifteen isolates of Salmonella survived 30 days under desiccation and one strain survived for one year and potentially could survive longer. Differences in the survival between different Salmonella serotypes, and isolates of the same serotype (S. Typhimurium), were noted. A 2-population Weibull model was used to model survival, since following an initial reduction in viability (72 h), no further reduction was seen. There was enhanced survival of Salmonella at lower temperatures and relative humidity, with the presence of food debris and when water was added. At a physiological level, attributes associated with osmoresistance (RDAR phenotype, motility, filamentation, EPS production) were not observed in all desiccation resistant strains, additionally survival was greater on surfaces rather than in hyperosmotic solutions. Desiccated cells did not show increased sodium hypochlorite and propanol resistance. To assess molecular survival mechanisms, three RNA extraction methods were compared and real-time RT-PCR was performed for 13 genes. All selected housekeeping genes showed change in expression therefore were not used. Genes in desiccation sensitive strain had higher fold change during desiccation than in resistant strain (aceA, nifU and otsB). The principles of HACCP were reviewed and a prerequisite management programme, based on a risk assessment of sources and vectors, was designed and applied in a low aw food factory, to help control Salmonella cross-contamination. These results suggest the potential for extended survival of Salmonella in food factories, describe the most suitable model to predict survival kinetics, give some insight into Salmonella survival mechanisms and stress responses under desiccation conditions and identify strains and methods for further research studies. The results also confirm the need to keep low aw factories free of food debris and to eliminate water to reduce Salmonella survival. Given the potential for Salmonella survival, the results also highlight the need for the control of cross contamination to the food product via an improved prerequisite management plan.

The recent identification of two novel influenza-like viruses in bats, H17N10 and H18N11 virus, and the discovery of serologically positive Eidolon helvum bats in Ghana for avian H9 virus prompted my hypothesis that, in addition to the large repertoire of zoonotic viruses hosted, bats may serve as asymptomatic reservoir species to conventional influenza A viruses found in birds and mammals. To begin to test this hypothesis, the susceptibility of three bat cell lines, derived from lung epithelial cells of Eidolon helvum, Carollia perspicillata and Tadarida brasiliensis (TB1-Lu), to low pathogenicity avian viruses (H2N3 [A/mallard duck/England/7277/06] virus and H6N1 virus [A/turkey/England/198/09] virus), and human viruses (USSR H1N1 virus [A/USSR/77] and pandemic H1N1 2009 virus [A/California/07/2009]) was determined. All three species of bat epithelial cells were found to be more robust and resistant to influenza virus infections than permissive MDCK cells. Infected bat cells produced lower levels of viral RNA and viral progeny, and were more viable than correspondingly treated MDCK cells. Interestingly, bat cells were more susceptible and replication permissive to avian than human influenza viruses. Among the bat cells, TB1-Lu cells were the least susceptible to influenza virus infection and that appears to be related to a lack of sialic acid α2,6-Gal receptors, mammalian virus-preferred host receptors, which were present in the other two bat species. The innate mechanisms underlying resistance to influenza virus infection in bats remains to be determined, however, inhibition of the JAK/STAT pathway was found not to affect virus production from infected bat cells suggesting that JAK/STAT signalling may not have a major role in influenza virus resistance in bat cells. Modulation of NF-κB signalling was found to affect virus production suggesting that tight regulation of NF-κB may be key in controlling the pro-inflammatory response to influenza infection in bat cells and warrants further investigation.