Importance of space and competition in optimizing genetic control strategies.

Advances in the genetic modification of organisms are creating new opportunities for the control of insect pests of both agriculture and public health significance. The timing and sex specificity of lethal transgene activation can be tailored to enhance the pest population control efficiency of mass-released, genetically modified insects. We developed mathematical models to determine the optimal timing and sex specificity of lethal transgene activation for the control of different types of pest population. We show that optimal release strategies are not only sensitive to the parameters governing growth of the population but also can be drastically affected by the inclusion of insect stage structuring, competition, and space. We emphasize the necessity of including these additional levels of complexity in future theoretical assessments as they are likely important considerations for designing transgenic organisms as well as their application in genetic control

How do biting disease vectors behaviourally respond to host availability?

BACKGROUND: Ecological theory predicts a diverse range of functional responses of species to resource availability; but in the context of human blood consumption by disease vectors, a simplistic, linear response is ubiquitously assumed. A simple and flexible model formulation is presented that extends the Holling's Types to account for a wider range of qualitatively distinct behaviours, and used to examine the impact of different vector responses to the relative availability of multiple blood-host species. RESULTS: Epidemiological models of falciparum malaria, Chagas disease and Lyme disease demonstrate that the standard, often implicit, assumption of a linear functional response can lead to spurious under- or over-estimates in disease transmission potential, across a full range of pathogen life-cycles. It is shown how the functional response in vector biting can augment disease intervention outcomes. Interactions between vector biting behaviour and uneven pathogen transmission probabilities between alternative hosts, as is the case for Chagas disease, can render infection more resilient to control. CONCLUSIONS: Both the novel response formula and the nested vector-borne disease structure offer a flexible framework that can be applied to other vector-borne diseases in assessing the role of this newly identified aspect of biting behavioural ecology

Models for the h cluster of the [FeFe]-hydrogenase: synthesis, protonation and electrochemical investigations

The investigations of the ability of the [FeFe]-hydrogenase models toward the electrocatalytic reduction of protons showed that the presence of protonation sites on the model complex is important to lower the overpotential of proton reduction and to enhance the catalytic activity. Figure 1 provides an overview for different derivatization strategies of various [FeFe]-hydrogenase models that are described in this thesis

Breaking Down the “Heritage not Hate” Movement’s Origin, Usage, and Effect on Race Relations in the Post Civil War Era

When the Confederacy first formed, its governmental symbolism and ideology mirrored that of the northern United States. The two Constitutions were incredibly similar – minus the South’s adjustments to further enhance the rights of states and slaveowners – with the Confederate government installing a Legislative Branch, an Executive Branch, and a Judicial Branch. In addition to this Constitutional similarity, the Confederacy also created a flag that looked similar to the United States’ that Confederate troops had trouble differentiating the two in combat. Following a chaotic Battle of Bull Run in July of 1861, General Pierre Gustave Toutant-Beauregard pushed for the creation of a new national flag, and when that was rejected, a battle flag. In September of the same year, Beauregard finalized the “Southern Cross” design of the Confederate Battle Flag. Though this exact flag was never installed as the official Confederate national flag, it has become one of the most recognizable symbols of the Confederate States of America and all it represents following the Civil War. It is that key phrase – “all it represents” – that serves as the foundation for this thesis. The battle flag and the Confederate States of America have become intertwined in meaning and symbolism, as you cannot have one without the other. With that in mind, I intend to analyze how the icon of one of the most shameful periods and practices in the United States’ history has persisted and been defended for much longer than the Confederacy lasted itself. Further, this thesis will study the effect of that persistence – and the broader Confederate memorialization it represents – on race relations in the postwar United States

The Purification and characterization of threonine dehydrogenase from Klebsiella pneumoniae and Enterobacter aerogenes

Threonine dehydrogenase has been purified to apparent homogeneity from Klebsiella pneumoniae and Enterobacter aerogenes. Purification was achieved by sequential chromatography on DEAE ion exchange, Blue Sepharose affinity gel, and Toyopearl HW-55s gel filtration. The amino-terminus for the enzyme in both organisms has been sequenced and placed the enzyme from K. pneumoniae with a class of long chain alcohol dehydrogenase family. The subunit molecular mass was estimated as 38.8 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, while an apparent native molecular mass of 154 kDa was shown by gel filtration chromatography, suggesting a tetrameric structure. As for the enzyme from E. aerogenes, it is described as a possible dimer with a native molecular mass estimate of 104.5 kDa, and a subunit molecular mass estimate of 43.1 kDa. This enzyme showed homology to a group of alcohol dehydrogenase I family with a preference to propanol as a substrate

Benchmarking matching color in composite restorations

The purpose of this study was to investigate the color samples (A2, A3 and B1) of three different brands of resin composites using dentine masses. 135 discs were prepared (5 plates for each thickness, color and brand of composite material). A colorimetric evaluation, using white and black background, was performed just after preparation. The color was measured corresponding to "Vita" scale and ΔL, Δa, Δb and ΔE values were calculated using a spectrophotometer. The results showed that Value, Chroma and Hue often differ even if the same commercial color and same thickness is used. In conclusion, this study showed that the perfect aesthetics restoration is possible combining individual abilities, experience and correct techniques

OTOLITH MASS ASYMMETRY IN CARANGOIDES CAERULEPINNATUS (RÜPPELL, 1830) (FAMILY: CARANGIDAE) COLLECTED FROM THE SEA OF OMAN

The sagittae mass asymmetry was studied in the teleost Carangoides caeruleopinnatus. The value of the asymmetry was calculated as the difference between the mass of the right and left paired otoliths, divided by average otolith mass. The results show that the absolute value of X in C. caeruleopinnatus does not depend on fish length and otolith growth rate, as it does in other symmetrical fish species. However, the absolute value of otolith mass difference increases with the fish length. The value of x falls between -0.2 and +0.2

Endectocide-treated cattle for malaria control: A coupled entomological-epidemiological model

The malaria vector landscape is dynamic and dependence on indoor control tools has drastically affected both species compositions and local mosquito biting behaviours. In the advent of spreading behavioural resilience and physiological resistance to insecticidal nets and house spray, approaches to target more zoophilic, outdoor-biting vectors are being sought with increased urgency. Endectocides are insecticides applied to hosts which are taken up by the vectors during biting, and recent field assessments have demonstrated favourable results of cattle treated with ivermectin, diflubenzuron, eprinomectin and fipronil. Models were constructed to account for the modern, diverse vector feeding behaviours and assess their role in shaping malaria transmission and control with cattle-treated endectocides. Efficacy of this novel approach to malaria control is shown to be strongly dependent not only on intrinsic host preferences of the vector but also on how this preference is augmented by variation in the encounter rates with alternative blood-hosts. Ecological scenarios are presented whereby endectocides used on cattle yield equivalent, and in some cases improved, efficacy over nets and spray in controlling malaria transmission. Interactions between mosquito biting behaviours and relative availabilities of alternative blood-host species have largely been neglected in malaria programmatic strategy but will increasingly underlie sustaining the successes of vector control initiatives