The growth, processing and characterisation of II-VI semiconductor structures

The work contained in this thesis focuses on the growth, processing and characterization of II-VI semiconductors for use in opto-electronic devices. Included are efforts to develop both II-VI based distributed Bragg reflectors (DBRs) utilising ZnMgSSe and ZnSe and the epitaxial lift-off (ELO) process pioneered at Heriot-Watt University (HWU). The optical properties of a range of different II-VI compounds (inc. ZnSe, MgS, MnS and ZnMgSSe) are measured using a range of techniques including photoluminescence spectroscopy (PL), optical transmission measurement and spectroscopic ellipsometry. From these measurements, a more accurate value for the bowing parameter of ZnCdSe of 0.37±0.05eV is determined. The effect of lifting structures using an MgS sacrificial layer is investigated by optical microscopy, optical transmission measurement and PL, to allow any structural changes to be determined. The ELO process is also extended to allow structures grown on InP substrates to be lifted by using a magnesium selenide (MgSe) sacrificial layer. The μ-PL measurements of a series of CdSe QDs grown on ZnMgSSe barriers are also reported and compared to previous work on other barrier materials (ZnSe and MgS). The causes of the jitter (spectral diffusion) seen in these samples is also investigated and discussed

The potential for dietary factors to prevent or treat osteoarthritis

Osteoarthritis (OA) is a degenerative joint disease for which there are no disease-modifying drugs. It is a leading cause of disability in the UK. Increasing age and obesity are both major risk factors for OA and the health and economic burden of this disease will increase in the future. Focusing on compounds from the habitual diet that may prevent the onset or slow the progression of OA is a strategy that has been under-investigated to date. An approach that relies on dietary modification is clearly attractive in terms of risk/benefit and more likely to be implementable at the population level. However, before undertaking a full clinical trial to examine potential efficacy, detailed molecular studies are required in order to optimise the design. This review focuses on potential dietary factors that may reduce the risk or progression of OA, including micronutrients, fatty acids, flavonoids and other phytochemicals. It therefore ignores data coming from classical inflammatory arthritides and nutraceuticals such as glucosamine and chondroitin. In conclusion, diet offers a route by which the health of the joint can be protected and OA incidence or progression decreased. In a chronic disease, with risk factors increasing in the population and with no pharmaceutical cure, an understanding of this will be crucial

The identification and significance of inputs to Anthrosols in North-West Europe

In recent years there has been a renewed interest in soils which are the result of past land management practices involving substantial additions of mineral and organic matter. However, there is still a substantial lack of detailed information on their formation. Anthrosols are distinguished by the presence of a deep top horizon and such soils were investigated at sites in Scotland, Denmark and The Netherlands. Field data and samples were collected from eight sites under arable cultivation, meadowland and woodland. Particle size distribution, pH, loss on ignition, ECEC, base saturation and total P were measured. Carbonaceous particles were identified through micromorphological analysis and the determination of O:C ratios using an electron microprobe. Despite the use of different inputs in recent centuries and different current land management, the resultant anthropogenic soils are remarkably similar in field and analytical properties. Nevertheless, subtle changes in particle size can be explained by parent material influences, material imported by farmers and by inputs by other processes such as by wind. The results from microprobe analysis demonstrate the importance of carbonaceous particles in storing phosphorus. Thus the inherent fertility of these Anthrosols can be explained in part by the application of carbonised material in the past

Superoxide dismutase downregulation in osteoarthritis progression and end-stage disease

Oxidative stress is proposed as an important factor in osteoarthritis (OA). To investigate the expression of the three superoxide dismutase (SOD) antioxidant enzymes in OA. SOD expression was determined by real-time PCR and immunohistochemistry using human femoral head cartilage. SOD2 expression in Dunkin–Hartley guinea pig knee articular cartilage was determined by immunohistochemistry. The DNA methylation status of the SOD2 promoter was determined using bisulphite sequencing. RNA interference was used to determine the consequence of SOD2 depletion on the levels of reactive oxygen species (ROS) using MitoSOX and collagenases, matrix metalloproteinase 1 (MMP-1) and MMP-13, gene expression. All three SOD were abundantly expressed in human cartilage but were markedly downregulated in end-stage OA cartilage, especially SOD2. In the Dunkin–Hartley guinea pig spontaneous OA model, SOD2 expression was decreased in the medial tibial condyle cartilage before, and after, the development of OA-like lesions. The SOD2 promoter had significant DNA methylation alterations in OA cartilage. Depletion of SOD2 in chondrocytes increased ROS but decreased collagenase expression. This is the first comprehensive expression profile of all SOD genes in cartilage and, importantly, using an animal model, it has been shown that a reduction in SOD2 is associated with the earliest stages of OA. A decrease in SOD2 was found to be associated with an increase in ROS but a reduction of collagenase gene expression, demonstrating the complexities of ROS function

Palliative care needs in patients hospitalized with heart failure (PCHF) study: rationale and design

Abstract Aims The primary aim of this study is to provide data to inform the design of a randomized controlled clinical trial (RCT) of a palliative care (PC) intervention in heart failure (HF). We will identify an appropriate study population with a high prevalence of PC needs defined using quantifiable measures. We will also identify which components a specific and targeted PC intervention in HF should include and attempt to define the most relevant trial outcomes. Methods An unselected, prospective, near-consecutive, cohort of patients admitted to hospital with acute decompensated HF will be enrolled over a 2-year period. All potential participants will be screened using B-type natriuretic peptide and echocardiography, and all those enrolled will be extensively characterized in terms of their HF status, comorbidity, and PC needs. Quantitative assessment of PC needs will include evaluation of general and disease-specific quality of life, mood, symptom burden, caregiver burden, and end of life care. Inpatient assessments will be performed and after discharge outpatient assessments will be carried out every 4 months for up to 2.5 years. Participants will be followed up for a minimum of 1 year for hospital admissions, and place and cause of death. Methods for identifying patients with HF with PC needs will be evaluated, and estimates of healthcare utilisation performed. Conclusion By assessing the prevalence of these needs, describing how these needs change over time, and evaluating how best PC needs can be identified, we will provide the foundation for designing an RCT of a PC intervention in HF

Persistent depression affects adherence to secondary prevention behaviors after acute coronary syndromes

Background: The persistence of depressive symptoms after hospitalization is a strong risk factor for mortality after acute coronary syndromes (ACS). Poor adherence to secondary prevention behaviors may be a mediator of the relationship between depression and increased mortality. Objective: To determine whether rates of adherence to risk reducing behaviors were affected by depressive status during hospitalization and 3 months later. Design: Prospective observational cohort study. Setting: Three university hospitals. Participants: Five hundred and sixty patients were enrolled within 7 days after ACS. Of these, 492 (88%) patients completed 3-month follow-up. Measurements: We used the Beck Depression Inventory (BDI) to assess depressive symptoms in the hospital and 3 months after discharge. We assessed adherence to 5 risk-reducing behaviors by patient self-report at 3 months. We used χ2 analysis to compare differences in adherence among 3 groups: persistently nondepressed (BDI<10 at hospitalization and 3 months); remittent depressed (BDI ≥10 at hospitalization; <10 at 3 months); and persistently depressed patients (BDI ≥10 at hospitalization and 3 months). Results: Compared with persistently nondepressed, persistently depressed patients reported lower rates of adherence to quitting smoking (adjusted odds ratio [OR] 0.23, 95% confidence interval [95% CI] 0.05 to 0.97), taking medications (adjusted OR 0.50, 95% CI 0.27 to 0.95), exercising (adjusted OR 0.57, 95% CI 0.34 to 0.95), and attending cardiac rehabilitation (adjusted OR 0.5, 95% CI 0.27 to 0.91). There were no significant differences between remittent depressed and persistently nondepressed patients. Conclusions: Persistently depressed patients were less likely to adhere to behaviors that reduce the risk of recurrent ACS. Differences in adherence to these behaviors may explain in part why depression predicts mortality after ACS. Key Words: cardiovascular diseases, depression, medication adherence, prevention, self car

Historic landscape management: a validation of quantitative soil thin-section analyses

The archaeological interpretation of past land management practices can be greatly enhanced through examination of soil thin sections. Features relating to manuring practice are among those key to interpreting agricultural practices. The sources and the pro¬cesses leading to the distribution of these manure materials may further improve knowledge of the past landscape utilisation. The use of quantitative analyses to examine soil thin sections opens the possibility of considering these relationships between manured areas in greater detail and to extract more subtle spatial and temporal changes in past management. In this study the validation of this methodology has been tested with quantitative image analysis methods used to examine manure inputs to a well-documented historical landscape of Papa Stour, Shetland, where intensive manuring has been practised until the 1960s. By using both historic and ethnographic evidence to validate the image analysis protocol, differences in spatial and temporal distribution are examined for the practices of manuring with both fuel residues and with turf. The validation of the hypotheses expected from ethnographic and historical data that quantitative soils-based evidence allows the definition of variations in manuring strategies and provides a more secure basis from which to interpret manuring management strategies in archaeological landscapes

Shell Neurons of the Master Circadian Clock Coordinate the Phase of Tissue Clocks Throughout the Brain and Body

Background: Daily rhythms in mammals are programmed by a master clock in the suprachiasmatic nucleus (SCN). The SCN contains two main compartments (shell and core), but the role of each region in system-level coordination remains ill defined. Herein, we use a functional assay to investigate how downstream tissues interpret region-specific outputs by using in vivo exposure to long day photoperiods to temporally dissociate the SCN. We then analyze resulting changes in the rhythms of clocks located throughout the brain and body to examine whether they maintain phase synchrony with the SCN shell or core. Results: Nearly all of the 17 tissues examined in the brain and body maintain phase synchrony with the SCN shell, but not the SCN core, which indicates that downstream oscillators are set by cues controlled specifically by the SCN shell. Interestingly, we also found that SCN dissociation diminished the amplitude of rhythms in core clock gene and protein expression in brain tissues by 50–75 %, which suggests that light-driven changes in the functional organization of the SCN markedly influence the strength of rhythms in downstream tissues. Conclusions: Overall, our results reveal that body clocks receive time-of-day cues specifically from the SCN shell, which may be an adaptive design principle that serves to maintain system-level phase relationships in a changing environment. Further, we demonstrate that lighting conditions alter the amplitude of the molecular clock in downstream tissues, which uncovers a new form of plasticity that may contribute to seasonal changes in physiology and behavior

Long-term Outcomes of Enhanced Depression Treatment in Patients with Acute Coronary Syndromes

Background: The Coronary Psychosocial Evaluation Studies trial demonstrated promising results for enhanced depression treatment to reduce cardiovascular risk of patients with acute coronary syndrome and comorbid depression, but the long-term effectiveness of this intervention is unclear. Methods: A total of 157 participants with persistent depression after hospitalization for acute coronary syndromes were enrolled in the Coronary Psychosocial Evaluation Studies trial. A total of 80 participants were allocated to 6 months of enhanced depression treatment, and 77 participants were allocated to usual care. We report on an additional 12 months of observational follow-up for the composite outcome of death or first hospitalization for myocardial infarction or unstable angina. Results: Although the intervention was previously shown to have favorable cardiovascular effects during the treatment period, we observed a significant time-by-treatment group interaction during extended follow-up (P = .008). Specifically, during the 6-month treatment period, death or hospitalization for myocardial infarction/unstable angina occurred in 3 participants (4%) in the treatment group compared with 11 participants (14%) in the usual care group (hazard ratio, 0.25; 95% confidence interval, 0.07-0.90; P = .03). In contrast, during 12 months of additional observational follow-up, 11 participants (14%) in the treatment group experienced the composite outcome of death or hospitalization for myocardial infarction/unstable angina compared with 3 participants (4%) in the usual care group (hazard ratio, 2.91; 95% confidence interval, 0.80-10.56; P = .10). Conclusions: Enhanced depression treatment was associated with a reduced risk of death or hospitalization for myocardial infarction/unstable angina during active treatment, but this effect did not persist after treatment ceased. Future research is needed to confirm our findings and to determine the optimal duration of depression treatment in patients with depression after acute coronary syndromes