Combined TEM - cathodoluminescence study of nitride semiconductor structures

This work presents the results of an investigation into the technique of combined TEM-Cathodoluminescence and its application to the study of GaN epitaxial layers grown by MOVPE and PAMBE on sapphire and LiAlO(_2) substrates respectively - and MOVPE grown In(_x)Ga(_1-x)N/GaN/A1(_2)O(_3) QW structures. The measurement of CL in a TEM allows spectral information to be correlated with structural information. In-situ electron beam degradation curves of panchromatic CL from GaN epilayers and In(_0.1)Ga(_0.9)N QW emission revealed a decline in the luminescence which could be attributed to the introduction of non-radiative recombination centres. The influence of thickness on both CL spectra and images was investigated experimentally and by modelling. A method of normalising STEM-CL images for thickness contrast was developed. Application of this normalisation to In(_0.1)Ga(_0.9)N QWs in cross-section revealed inhomogeneous CL with bright regions 200-700nm in width. No systematic relationship was identified between luminescence at the QW peak emission wavelength, QW(_A), and luminescence at QW(_A) ±10nm. This finding does not support the hypothesis that variation in QW CL brightness is due to local compositional fluctuation. However, clusters of threading dislocations were shown to suppress QW luminescence and are suggested as a cause for the observed inhomogeneity in luminescence. A statistical analysis of (dislocation related) V-pits in In(_x)Ga(_1-x)N MQW samples revealed clustering of pits on a length scale of 60-120nm, but no long range clustering indicative of sub-grain boundaries was found. Finally TEM-CL spectra and monochromatic line-scans were used to show that bundles of basal plane stacking faults in M-plane GaN epitaxial layers grown on LiAlO(_2) emit radiatively at 3.3-3.35eV (l00K). The radiative transition energy is consistent with models in the literature that consider basal plane stacking faults to be layers of cubic GaN in the wurtzite matrix which act as type II QWs

Modeling Bird Species Occurrence in Current and Future Landscapes

With mounting evidence that global temperatures have increased significantly over the last century and the projections of greater changes in climate by the end of this century, understanding the potential consequences of these changes for species is essential to conservation efforts. Here I evaluate the potential response of birds to projected climate change by using regression tree analysis to create models of species distributions under current conditions from Breeding Bird Survey data and then project these models onto General Circulation Model (GCM) scenarios of global climate change. Before modeling species responses to climate change, I selected seventeen bird species to evaluate several considerations that could influence the ability to effectively model species distributions. First, I addressed the spatial resolution of the analysis. GCM data are readily available at a relatively coarse-grain compared to bird data. Since the spatial resolution of an analysis can greatly affect the outcome, I, therefore, assessed the consequences of modeling bird abundance at the 640-km2 hexagonal grid (fine-grain) and the county resolution (coarse-grain) in the eastern United States. The results indicated that county resolution models produced good predictions of current bird distributions. Next, I compared two sets of climate data to ensure that the climate outputs from GCMs were as effective in modeling bird distributions as climate variables currently used in ecological studies. There were no differences of the overall model goodness of fit between the two sets of species models. The results from these analyses indicated that effective models of bird distributions at the county resolution could be constructed, provided both climate and land cover variables were present as predictors. Following these evaluations I was able to model current abundance for 152 bird species. These models were projected onto two GCM scenarios. The projected response of birds under the two GCM scenarios varied greatly among species. Overall, both GCM scenarios projected approximately 49% of the species to decrease markedly and 22% to increase in their eastern United States populations. These results indicate the potential for large shifts in bird distributions in response to global climate change. The heightened awareness of our Earth\u27s increasing temperature has been linked to the rapid increase in greenhouse gases. Planting forests on marginal agricultural land has emerged as a promising proposal to sequester excess carbon dioxide, but none of these afforestation studies have considered the costs or benefits associated with impacts on wildlife. By combining information on current forest and farmland bird abundances with the results from simulations of carbon sequestration policies in South Carolina, Maine, and southern Wisconsin, it is possible to quantify the impacts of land use decisions on bird populations. I estimated losses respectively of 12.2 %, 10.8 %, and 1 1.7 % in farmland birds and gains of 2.5 %, 3.2 %, and 21.8 % in forest species in South Carolina, Maine, and southern Wisconsin. The results from this analysis reveal the importance of considering the effects of large-scale land use decisions on wildlife

Extreme Rapid Weight Loss and Rapid Weight Gain Observed in UK Mixed Martial Arts Athletes Preparing for Competition

There is a lack of research documenting the weight-making practices of mixed-martialarts (MMA) competitors. The purpose of the investigation was to quantify the magnitude and identify the methods of rapid weight loss (RWL) and rapid weight gain(RWG) in MMA athletes preparing for competition. Seven athletes (mean ± SD, age 24.6 ± 3.5 yrs, body mass 69.9 ± 5.7 kg, competitive experience 3.1 ± 2.2 yrs) participated in a repeated-measures design. Measures of dietary intake, urinary hydration status, and body mass were recorded in the week preceding competition. Body mass decreased significantly (p<0.0005) from baseline by 5.6 ± 1.4 kg (8 ± 1.8%). During the RWG period (32 ± 1 hours) body mass increased significantly (p<0.001) by 7.4 ± 2.8 kg (11.7 ± 4.7%), exceeding RWL. Mean energy and carbohydrate intake were 3176 ± 482 kcal.day-1 and 471 ± 124 g.day-1, respectively. At the official weigh-in 57% of athletes were dehydrated (1033 ± 19 mOsmol.kg-1) and the remaining 43% were severely dehydrated (1267 ± 47 mOsmol.kg-1). Athletes reported using harmful dehydration-based RWL strategies, including sauna (43%) and training in plastic suits (43%). Results demonstrated RWG greater than RWL, this is a novel finding and may be attributable to the 32 hour duration from weigh-in till competition. The observed magnitude of RWL and strategies used are comparable to those which have previously resulted in fatalities. Rule changes which make RWL impractical should be implemented with immediate effect to ensure the health, safety and wellbeing of competitors

Studies on the anti-inflammatory effect of S-Adenosyl-L-methionine

1. S-adenosyl-L-methionine (SAMe) had no effect on cytochrome C reduction by superoxide generated from xanthine oxidase except at high concentrations. This was due to direct inhibition of the enzyme. 2. SAMe inhibited the neutrophil respiratory burst , measured by luminol enhanced chemiluminescence, to FMLP and zymosan A but not to PMA. 3. Adenosine and methylthioadenosine (MTA) inhibited the respiratory burst elicited by FMLP. 4. SAMe inhibited the phagocytosis of latex particles by neutrophils at high concentrations but methionine and S-adenosyl L-homocysteine had no effect. 5. Treatment with SAMe had no effect on cell infiltration or PGE2 production in 6-day air pouches. 6. Treatment with SAMe at the optimum dose of 50mg/kg inhibited the early phases of carrageenan induced rat hind paw inflammation but had a lesser effect on the secondary response. The antiinflammatory effect was sustained after inhibiton of polyamine synthesis. 7. SAMe increased liver putrescine levels in the presence and absence of inflammation Spermidine levels were increased in the presence of inflammation but spermine levels were unaffected by any of the treatments. 8. MT A and adenosine increased liver putrescine and spermidine levels 9. Treatment with SAMe had no effect on the polyamine status of blood. lO.Treatment with SAMe had no effect on the levels of glutathione in liver or blood. 11.SAMe and MTA inhibited histamine and platelet-activating factor (PAF) induced hind paw inflammation but had no effect on inflammation induced by dextran, zymosan, compound 48/80, 5-hydroxytryptamine, arachidonic acid or glucose oxidase. MTA was more effective than SAMe. 12. PAP-induced rat hind paw inflammation was inhibited by isoprenaline and verapamil. Combinations of these drugs with SAMe or MT A had no further enhancement of effect. 13. Incubation of rat PMNLs with [14c ] SAMe increased the intracellular levels of S-adenosyl-L-homocysteine in a dose dependent manner, but had no effect on the intracellular levels of SAMe, adenosine or MT A. 14. Pharmacokinetic studies of plasma SAMe following a single dose of the drug (50mg/kg) i.p. demonstrated that SAMe is rapidly absorbed and metabolise

"Life is harder" : the perceived impact of a newspaper closure on community members

This study presents findings from 18 in-depth interviews with residents of a recent news desert and offers a systematic qualitative investigation of the perceived impact of a newspaper's closure on community members' everyday lives and, just as important, their sense of community. This case study, using the psychological theory of sense of community as its theoretical framework, shows a noticeable negative effect on community members' sense of community, with participants missing celebrated gatherings, suffering from an increased sensation of isolation and diminished pride in the community. In addition, without newspaper reporters stationed in the county, residents function as reporters themselves, laboring to obtain information. Overall, these findings present a picture of life in Caroline County, Virginia, following the Caroline Progress' closure after 99 years of service to the county.by Nicholas Emanuel MatthewsIncludes bibliographical reference

Extreme Rapid Weight Loss and Rapid Weight Gain Observed in UK Mixed Martial Arts Athletes Preparing for Competition

There is a lack of research documenting the weight-making practices of mixed-martialarts (MMA) competitors. The purpose of the investigation was to quantify the magnitude and identify the methods of rapid weight loss (RWL) and rapid weight gain(RWG) in MMA athletes preparing for competition. Seven athletes (mean ± SD, age 24.6 ± 3.5 yrs, body mass 69.9 ± 5.7 kg, competitive experience 3.1 ± 2.2 yrs) participated in a repeated-measures design. Measures of dietary intake, urinary hydration status, and body mass were recorded in the week preceding competition. Body mass decreased significantly (p<0.0005) from baseline by 5.6 ± 1.4 kg (8 ± 1.8%). During the RWG period (32 ± 1 hours) body mass increased significantly (p<0.001) by 7.4 ± 2.8 kg (11.7 ± 4.7%), exceeding RWL. Mean energy and carbohydrate intake were 3176 ± 482 kcal.day-1 and 471 ± 124 g.day-1, respectively. At the official weigh-in 57% of athletes were dehydrated (1033 ± 19 mOsmol.kg-1) and the remaining 43% were severely dehydrated (1267 ± 47 mOsmol.kg-1). Athletes reported using harmful dehydration-based RWL strategies, including sauna (43%) and training in plastic suits (43%). Results demonstrated RWG greater than RWL, this is a novel finding and may be attributable to the 32 hour duration from weigh-in till competition. The observed magnitude of RWL and strategies used are comparable to those which have previously resulted in fatalities. Rule changes which make RWL impractical should be implemented with immediate effect to ensure the health, safety and wellbeing of competitors

Interactive molecular docking with haptics and advanced graphics

Biomolecular interactions underpin many of the processes that make up life. Molecular docking is the study of these interactions in silico. Interactive docking applications put the user in control of the docking process, allowing them to use their knowledge and intuition to determine how molecules bind together. Interactive molecular docking applications often use haptic devices as a method of controlling the docking process. These devices allow the user to easily manipulate the structures in 3D space, whilst feeling the forces that occur in response to their manipulations. As a result of the force refresh rate requirements of haptic devices, haptic assisted docking applications are often limited, in that they model the interacting proteins as rigid, use low fidelity visualisations or require expensive propriety equipment to use. The research in this thesis aims to address some of these limitations. Firstly, the development of a visualisation algorithm capable of rendering a depiction of a deforming protein at an interactive refresh rate, with per-pixel shadows and ambient occlusion, is discussed. Then, a novel approach to modelling molecular flexibility whilst maintaining a stable haptic refresh rate is developed. Together these algorithms are presented within Haptimol FlexiDock, the first haptic-assisted molecular docking application to support receptor flexibility with high fidelity graphics, whilst also maintaining interactive refresh rates on both the haptic device and visual display. Using Haptimol FlexiDock, docking experiments were performed between two protein-ligand pairs: Maltodextrin Binding Protein and Maltose, and glutamine Binding Protein and Glucose. When the ligand was placed in its approximate binding site, the direction of over 80% of the intra-molecular movement aligned with that seen in the experimental structures. Furthermore, over 50% of the expected backbone motion was present in the structures generated with FlexiDock. Calculating the deformation of a biomolecule in real time, whilst maintaining an interactive refresh rate on the haptic device (> 500Hz) is a breakthrough in the field of interactive molecular docking, as, previous approaches either model protein flexibility, but fail to achieve the required haptic refresh rate, or do not consider biomolecular flexibility at all

The Potential Role of Sigma-1 Receptor in Combating Alzheimer's Disease

Alzheimer’s Disease (AD) is a progressive neurodegenerative disorder and is the predominant cause of senescent dementia. As of today, no existing drug has the efficacy to reverse/counteract the cognitive deficiency associated with AD. However, researchers have for some time been intrigued by the roles of sigma-1 receptors (Sig-1R) in various neurological and psychological disorders. This is the current understanding of the Sig-1R and how this receptor works in the brain. Sig-1R assists in numerous cellular processes such as neuronal plasticity and oxidative stress, to name a few, which play a role in shaping memory and learning. The receptor has multiple various drugs that can target it, which could potentially assist in repairing cognitive impairment in AD. However, there are copious potential challenges that need to be overcome before any more significant advances are made in this field. This review aims to generate more curiosity and research into the Sig-1R combating AD