A study into compression ring dynamics using response surface methodology

For decades the operational dynamics of the compression ring during operation, have been subject to debate. A complex computer simulation, using Design Of Experiments (DOE) methodology, was developed to study the effect of the compression ring rotation during running-in stages. Response Surface (RS) has been used to optimise ring displacement, as function of ring mass, width and radius. The optimised surface response has been compared to used compression rings and has shown a 2% variation between calculated and measured values

In contrast to pundits’ claims, Barack Obama won reelection because of the economy – not despite it

Many media post-mortems of the 2012 presidential race assume that the sluggish economy made Mitt Romney the favorite, but that President Obama prevailed due to a combination of his more likeable personality, a superior ground-game and an effective early advertising blitz, as well as Romney’s campaign mistakes. Implicitly, this narrative suggests that voters are easily swayed by media ads, candidate blandishments, and other campaign tactics, and that unexpected events, such as candidate gaffes, play a decisive role in electoral outcomes. Matthew Dickinson argues that Obama’s victory owes much more to the traditional fundamentals, particularly incumbency status and the economy, that usually determine the outcome of presidential elections

Expression patterns of genes involved in the defense and stress response of Spiroplasma citri infected Madagascar Periwinkle Catharanthus roseus.

Madagascar periwinkle is an ornamental and a medicinal plant, and is also an indicator plant that is highly susceptible to phytoplasma and spiroplasma infections from different crops. Periwinkle lethal yellows, caused by Spiroplasma citri, is one of the most devastating diseases of periwinkle. The response of plants to S. citri infection is very little known at the transcriptome level. In this study, quantitative real-time PCR (RT-qPCR) was used to investigate the expression levels of four selected genes involved in defense and stress responses in naturally and experimentally Spiroplasma citri infected periwinkles. Strictosidine β-glucosidase involved in terpenoid indole alkaloids (TIAs) biosynthesis pathway showed significant upregulation in experimentally and naturally infected periwinkles. The transcript level of extensin increased in leaves of periwinkles experimentally infected by S. citri in comparison to healthy ones. A similar level of heat shock protein 90 and metallothionein expression was observed in healthy, naturally and experimentally spiroplasma-diseased periwinkles. Overexpression of Strictosidine β-glucosidase demonstrates the potential utility of this gene as a host biomarker to increase the fidelity of S. citri detection and can also be used in breeding programs to develop stable disease-resistance varieties

Generating Narratives from Personal Digital Data: Using Sentiment, Themes, and Named Entities to Construct Stories

As the quantity and variety of personal digital data shared on social media continues to grow, how can users make sense of it? There is growing interest among HCI researchers in using narrative techniques to support interpretation and understanding. This work describes our prototype application, ReelOut, which uses narrative techniques to allow users to understand their data as more than just a database. The online service extracts data from multiple social media sources and augments it with semantic information such as sentiment, themes, and named entities. The interactive editor automatically constructs a story by using unit selection to fit data units to a simple narrative structure. It allows the user to change the story interactively by rejecting certain units or selecting a new narrative target. Finally, images from the story can be exported as a video clip or a collage

The impacts of heat-wave conditions on reproduction in a model insect, Tribolium castaneum

Climate change will increase the frequency, intensity and duration of weather extremes including heat-waves, which could have important consequences for biodiversity. This thesis examines the direct influences of thermal stress associated with heat-wave conditions on reproduction in a model insect in order to understand how animal populations might be affected by climate change. Fertility reductions in homeotherms due to thermal stress are well documented, but effects on ectotherms have received little attention. In the first half of this thesis, the flour beetle model Tribolium castaneum is used to measure the impacts of heat-wave conditions on reproductive fitness in males and females, and the proximate mechanisms behind any impacts. I find that the reproductive fitness of males, but not females, is impacted by heat-wave conditions. Female fecundity is not affected when mating with heat stressed males, but egg hatch and pupal eclosion rates are reduced. Transgenerational effects were not found beyond the pupal stage. In experimental examinations of mating behaviour, males exposed to heat-wave conditions were slower to initiate mating and mated less frequently, but still achieving sufficient matings that would normally allow full female fertility. However, ejaculate sperm numbers were reduced more than five-fold following a simulated heat-wave, partly explaining how male reproductive fitness is halved following exposure to a heat-wave. In addition to an impact on male fertility and sperm production, I also found clear evidence that sperm in female storage were also sensitive to heat-wave conditions, with significant declines in female reproductive fitness if they had already mated and contained sperm, but no effects if the heat-wave was experienced before mating and sperm storage. This sensitivity of male fertility to heat-wave conditions could generate selection on both males and females to respond. In the second half of the project, the male and female responses to thermal stress and their impacts across generations were investigated. Females were found to be able to rescue their fertility when facing matings with heat stressed males by mating polyandrously, restoring their reproductive output to normal levels. However, I found no evidence that females strategically or facultatively adjusted their remating behaviour to compensate for reductions in fertility condition after thermal stress, and multi-generational male responses to elevated ambient temperature regimes showed no evidence for an ability to acclimate or adapt to heat-wave conditions. This thesis advances our knowledge of how one important trait for population viability and biodiversity can be impacted by climate change and increases in extreme weather conditions. It offers directions for future research to investigate the drivers of temperature-induced male fertility loss, and suggestions for how management efforts might be focused to mitigate the impacts of heat-wave conditions on reproduction in ectotherm

Adaptive thermal plasticity enhances sperm and egg performance in a model insect

Rising and more variable global temperatures pose a challenge for biodiversity, with reproduction and fertility being especially sensitive to heat. Here, we assessed the potential for thermal adaptation in sperm and egg function using Tribolium flour beetles, a warm-temperate-tropical insect model. Following temperature increases through adult development, we found opposing gamete responses, with males producing shorter sperm and females laying larger eggs. Importantly, this gamete phenotypic plasticity was adaptive: thermal translocation experiments showed that both sperm and eggs produced in warmer conditions had superior reproductive performance in warmer environments, and vice versa for cooler production conditions and reproductive environments. In warmer environments, gamete plasticity enabled males to double their reproductive success, and females could increase offspring production by one-third. Our results reveal exciting potential for sensitive but vital traits within reproduction to handle increasing and more variable thermal regimes in the natural environment

Molecular characterization of Phytophthora palmivora responsible for bud rot disease of oil palm in Colombia

Bud rot disease is a damaging disease of oil palm in Colombia. The pathogen responsible for this disease is a species of oomyctes, Phytophthora palmivora which is also the causal pathogen of several tropical crop diseases such as fruit rot and stem canker of cocoa, rubber, durian and jackfruit. No outbreaks of bud rot have been reported in oil palm in Malaysia or other Southeast Asian countries, despite this particular species being present in the region. Analysis of the genomic sequences of several genetic markers; the internal transcribe spacer regions (ITS) of the ribosomal RNA gene cluster, beta-tubulin gene, translation elongation factor 1 alpha gene (EF-1α), cytochrome c oxidase subunit I & II (COXI and COXII) gene cluster along with amplified fragment length polymorphism (AFLP) analyses have been carried out to investigate the genetic diversity and variation of P. palmivora isolates from around the world and from different hosts in comparison to Colombian oil palm isolates, as one of the steps in understanding why this species of oomycetes causes devastating damage to oil palm in Latin America but not in other regions. Phylogenetic analyses of these regions showed that the Colombian oil palm isolates were not separated from Malaysian isolates. AFLP analysis and a new marker PPHPAV, targeting an unclassified hypothetical protein, was found to be able to differentiate Malaysian and Colombian isolates and showed a clear clade separations. Despite this, pathogenicity studies did not show any significant differences in the level of aggressiveness of different isolates against oil palm in glasshouse tests

A Comparative Study of the Flora and Soils of Great Duck and Little Duck Islands, Maine, USA

Strong environmental gradients and varied land-use practices have generated a mosaic of habitats harboring distinct plant communities on islands on the coast of Maine. Botanical studies of Maine\u27s islands, however, are generally limited in number and scope. Baseline studies of Maine\u27s islands are necessary for assessing vegetation dynamics and changes in habitat conditions in relation to environmental impacts imposed by climate change, rising sea levels, invasive species, pests and pathogens, introduced herbivores, and human disturbance. We conducted a survey of the vascular plants and soils of forest, field, and ocean-side communities of Great Duck and Little Duck Islands, ME. These islands differ in environmental and land-use features, and in particular the presence of mammalian herbivores; Great Duck Island has had over a century of continuous mammalian herbivory while Little Duck Island has been largely free of mammalian herbivores over the last 100 years. We recorded 235 vascular plant species in 61 families on the Duck Islands, 106 of which were common to both islands. The composition, abundances, and diversity of plant species substantially differed within similar plant communities between the islands. These differences were particularly evident in the forest communities where Little Duck Island had significantly greater sapling regeneration and a more recent peak in tree recruitment. Soil properties also significantly differed between these islands, with a higher pH in all three communities and higher P, Ca, and K in field, forest, and ocean-side communities, respectively, on Little Duck Island, and higher soluble salts in forest and ocean-side communities of Great Duck Island. Together, our findings suggest that soil characteristics and the dominance and regeneration of vascular plant species can differ substantially even between adjacent islands with otherwise similar geologic characteristics and glacial history, and that mammalian herbivory along with other ecological factors may be important drivers of these differences

Dynamic modelling of compression ring conformability in high performance engines

Internal combustion (IC) engines have been the predominant technology for sourcing or generating power for over 100 years. The fundamental function of engines has not changed since there first introduction. By combusting fuel within the chamber causes a pressure build from the expanding gasses pushing the piston assembly through the cylinder, this linear action is then translated to rotation through the crankshaft to generate work. During combustion the gasses will try to move past the piston and into the crankcase, to deter this from occurring piston rings are introduced. Thus rings are designed to be in tight contact to the cylinder wall, and is subject to friction and wear as it travels up and down the cylinder wall. When a new ring pack is introduced, a running-in process is required. This involves running the engine at a variation of speeds for set times, typically defined by the manufacturer. While this procedure is executed the compression ring will undergo a series of thermodynamic morphological stages, the material will change shape due to the heat from the combustion process and suffer material loss due to the friction wear between cylinder wall and ring face. This thesis examines the impact of the running-in method on the compression ring and its performance. The work presented shows a novel numerical method that offers the first simulated solution to compression ring rotation around the piston crown and its impact on the engine performance. This has been achieved by adopting simultaneously two modelling packages to compute dynamics and contact mechanics for a more accurate multiphysics result. Using this model a coating refinement has been developed, offering a new chamfer change to the present ISO standard ensuring a longer coating operational life

A Simulation Study into the Use of Polymer Based Materials for Core Exoskeleton Applications

A core/trunk exoskeleton design has been produced that is aimed to assist the raise to stand motion. A 3D model was produced to examine the use of additive manufacturing as a core method for producing structural components for the exoskeleton presented. The two materials that were modelled for this simulation work were Polylatic acid (PLA) and polyethylene terephthalate with carbon (PET-C), and the central spinal cord of the design being Nitrile rubber. The aim of this study was to examine the use of 3D printed materials as the main skeletal structure to support the core of a human when moving raising from a resting position. The objective in this work was to identify if the 3D printable materials could be offered as an equivalent alternative to conventional more expensive materials, thus allow for greater access for production for home maintenance. A maximum load of lift force was calculated, and this was incrementally reduced to study the effects on the material. The results showed a total number of 8 simulations were run to study the core in conditions with no muscular support through to 90% of operational support. The study presents work in the form of a core/trunk exoskeleton that presents 3D printing as a possible alternative to conventional manufacturing