Miniaturisation of sensory systems in ants

The main focus of this thesis is the study of sensory systems in the context of changing body-size. In particular the study of ant sensory systems and how these are shaped by miniaturisation. The study of insect visual ecology and physiology is used as a basis to develop a framework for the study of ant antennal sensilla and chemosensation, to interpret anatomical variation from a functional and organ design perspective. This thesis reviews the anatomy and nomenclature of antennal sensilla through two case studies on an extremely large species Myrmecia pyriformis and a small species Temnothorax rugatulus. These two studies additionally quantify intraspecific variation and discuss the potential functional consequences of this variation for self-organising insect societies and task allocation. A large scale comparative study takes the tools developed in previous chapters to focus in on how chemosensilla vary in their numbers, size and distribution through the Fomicid phylogeny. The gross anatomy of the antenna and changes in shape from club to filiform antennae are described in detail. Anatomical data are analysed to identify scaling trends and potential adaptations driven by miniaturisation. Ecological and phylogenetic considerations are discussed wherever relevant. The wide ranging impacts of body size changes are reviewed, incorporated into the interpretation of results and used to propose promising avenues for future research. Finally, ant body size and some of the different methods used in the literature to measure size and size variability are critically analysed. The functional implications of body size variability within species are discussed using Iridomyrmex purpureus as an example. This thesis makes use of a variety of microscopy techniques. In addition to the methods sections of each chapter a dedicated methods chapter is included. This chapter reviews some of the techniques used in the main data chapters and in the additional publications produced over the course of this thesis

From Large to Small, from Day to Night: The Sensory Costs of Miniaturisation in Ants

This Honours thesis examines sensory adaptations of the compound eyes and antennal sensilla in response to diminishing body size and photic niche. It examines four different ant species using scanning electron microscopy and histological techniques

A two-time scale simulation for dynamic analysis of power systems

peer reviewedThis paper proposes a two-time scale simulation approach of both short-term and long-term dynamics in power systems. The short-term transient period is analyzed by a full-time scale simulation while a quasi-steady state model of the power system is used to simulate long-term dynamics. The proposed method is inspired of Singular Perturbation theory to model the interaction between the short-term and long-term dynamics. Based on this interaction, a suitable criterion to determine when the quasi-steady state model of a power system can be considered as a uniform approximation of the full-time scale model is proposed, which also determines the appropriate switching time between models. The proposed method is demonstrated on the 10-machine, 39-bus New England system and a 46-machine, 190-bus equivalent Mexican system

Modelo Credit Scoring PYMES para la medición del riesgo de morosidad de pequeña y mediana empresa : un caso de aplicación en entidad financiera

Proyecto de graduación (Licenciatura en Administración de Empresas. Énfasis en Finanzas) Instituto Tecnológico de Costa Rica, Escuela de Administración de Empresas, 2013.El presente proyecto de graduación consiste en un estudio técnico acerca de la posible existencia de métodos y herramientas que utiliza una entidad financiera para el análisis de riesgo de una empresa PYMES interesada en optar por un crédito empresarial. Así mismo este documento propone una herramienta que concentra los elementos más relevantes en el análisis inicial de un nuevo cliente o persona jurídica potencial para optar por un financiamiento bancario. Dado lo anterior el proyecto se estructura de la siguiente manera: Capítulo I Generalidades de la investigación, Capítulo II Marco Metodológico, Capítulo III Revisión del Estudio del Arte, Capítulo IV Puesta en práctica, Capítulo V Concepción de la MATRIZ SCORING PYMES, Capítulo VI Desarrollo y Análisis Estructural, Capítulo VII Conclusiones y Capitulo VIII Recomendaciones

Effect of the Reduction Temperature of PdAg Nanoparticles during the Polyol Process in the Ethanol Electrooxidation Reaction

This work reports the effect of reduction temperature during the synthesis of PdAg catalysts through the polyol process and their evaluation in the ethanol electrooxidation reaction (EOR). The characterization was performed using Transmission Electron Microscopy (TEM) and X-Ray Diffraction (XRD). The electrochemical evaluation for the ethanol electrooxidation reaction was implemented in alkaline medium using chronoamperometry (CA) and cyclic voltammetry (CV). An important effect of the reduction temperature on electroactivity and catalytic stability was observed: both the maximum current density and the catalytic stability were higher in the catalyst synthesized at the highest temperature (135°C). This performance was associated with the extent of the interaction between Pd and Ag which was measured in terms of the structural expansion of Pd

Techniques for investigating the anatomy of the ant visual system

This article outlines a suite of techniques in light microscopy (LM) and electron microscopy (EM) which can be used to study the internal and external eye anatomy of insects. These include traditional histological techniques optimized for work on ant eyes and adapted to work in concert with other techniques such as transmission electron microscopy (TEM) and scanning electron microscopy (SEM). These techniques, although vastly useful, can be difficult for the novice microscopist, so great emphasis has been placed in this article on troubleshooting and optimization for different specimens. We provide information on imaging techniques for the entire specimen (photo-microscopy and SEM) and discuss their advantages and disadvantages. We highlight the technique used in determining lens diameters for the entire eye and discuss new techniques for improvement. Lastly, we discuss techniques involved in preparing samples for LM and TEM, sectioning, staining, and imaging these samples. We discuss the hurdles that one might come across when preparing samples and how best to navigate around them.This work was supported by a graduate scholarship to FRE and grants from the Australian Research Council (DE120100019, FT140100221, DP150101172)

Proper motions of the HH1 jet

We describe a new method for determining proper motions of extended objects, and a pipeline developed for the application of this method. We then apply this method to an analysis of four epochs of [S~II] HST images of the HH~1 jet (covering a period of $\sim 20$~yr). We determine the proper motions of the knots along the jet, and make a reconstruction of the past ejection velocity time-variability (assuming ballistic knot motions). This reconstruction shows an "acceleration" of the ejection velocities of the jet knots, with higher velocities at more recent times. This acceleration will result in an eventual merging of the knots in $\sim 450$~yr and at a distance of $\sim 80"$ from the outflow source, close to the present-day position of HH~1.Comment: 12 pages, 8 figure

Improved Performance of an Epoxy Matrix as a Result of Combining Graphene Oxide and Reduced Graphene

We present an easy and effective way to improve the mechanical properties of an epoxy matrix by reinforcing it with a combination of graphene oxide (GO) and reduced graphene oxide (RGO). These nanocomposites were prepared with different load of nanofillers: 0.1, 0.4, 0.7, 1.0 wt% and a neat epoxy. Ratios of graphene oxide and reduced graphene (GO : RGO) employed were: 0 : 1, 0.25 : 0.75, 0.5 : 0.5, 0.75 : 0.25, and 1 : 0. Results show that with only 0.4 wt% and a ratio 0.2 : 0.75 of GO : RGO, tensile strength and tensile toughness are 52% and 152% higher than neat epoxy while modulus of elasticity was improved ~20%. The obtained results suggest that it is possible achieve advantageous properties by combining graphene in oxidized and reduced conditions as it shows a synergic effect by the presence of both nanofillers