Essays on immigration, innovation, and trade

This thesis comprises three essays on immigration, innovation, and trade. The first essay utilizes an enhanced gravity model to estimate the effect of lagged immigration waves on Canadian imports and exports, by province. Empirically, this model was tested using Canadian data on import and export flows to the top 40 countries of origin for immigrants to Canada based upon the composition of the most recent wave of immigrants. The results are consistent with previous studies, where immigrants increased both import and export trade flows. By adding the provincial immigrant wave variable, it was also found that new immigrants affect imports almost immediately, whereas for exports, the immigrant effect is not significant for at least 5 years and may take as long as 20 years to reach full impact.The second essay utilizes an enhanced gravity model to estimate the effect of innovative capability on Canadian provincial exports to Canada’s top 60 importing countries. Empirically, this model was tested using Canadian data on export flows to Canada’s top 60 importing countries. The results are supportive of a province’s innovative capability leading to increased exports, where innovative capacity is measured by international patents, scientific journal articles, and R&D expenditures. For example, in terms of innovative capacity as measured by international (U.S.) patents, provinces with higher levels of international patents had higher levels of total exports, where this effect was greater for exports to developing versus developed countries. Furthermore, provincial R&D expenditures as well as the number of provincial scientific publications (in addition to provincial international patents) were found to be significant drivers in increasing the amount of provincial hi-tech exports to developed countries.The third essay utilizes an augmented national ideas production function to examine skilled immigrants’ impact on Canadian innovation at the provincial level. Empirically, this model was tested using Canadian data by province on innovation flow over an 11 year time period, where innovation flow is defined in terms of international (U.S.) patents. It was found that skilled immigrants, who are proficient in either English or French, have a significant and positive impact on innovation flow in their home province. Further, in examining skilled immigrants by source region, it was found that skilled immigrants from developed countries have the greatest impact on their home province’s innovation flow. This is true of North American/European skilled immigrants for all skill-level categories including language proficiency, education, and immigrant class. For immigrants from developing countries, only highly educated Eastern Europeans and Low Income Asians classified as “Independent Workers” are both significant and positively related to their home province’s innovation flow

Three-dimensional, time-resolved velocity and density measurements of the stratified shear flow in an inclined duct

Laboratory experiments on the stratified shear flow in an inclined duct are reported. Stratified turbulence is observed in this two-layer exchange flow, whose dissipation is controlled by the duct inclination and compares in intensity with that observed in geo- physical contexts. A setup enabling three-dimensional (3D) simultaneous Particle Image Velocimetry (PIV) and Laser-Induced Fluorescence (LIF) is presented, and applied to the visualisation of Holmboe waves. Such capabilities are believed to be key to advance our understanding of the dynamics and mixing of stratified turbulence in the near future

The clinical application of PET/CT: a contemporary review

The combination of positron emission tomography (PET) scanners and x-ray computed tomography (CT) scanners into a single PET/CT scanner has resulted in vast improvements in the diagnosis of disease, particularly in the field of oncology. A decade on from the publication of the details of the first PET/CT scanner, we review the technology and applications of the modality. We examine the design aspects of combining two different imaging types into a single scanner, and the artefacts produced such as attenuation correction, motion and CT truncation artefacts. The article also provides a discussion and literature review of the applications of PET/CT to date, covering detection of tumours, radiotherapy treatment planning, patient management, and applications external to the field of oncology

Ex-vivo perfusion bioassay : an excellent technique to measure the bioactivity of inhalable insulin coated microcrystals

Purpose: To measure the bioactivity of inhalable insulin coated microcrystals using a perfusion bioassay that measures its vasodilatory effect on smooth muscle arterial tissue. Methods: The bioactivity of an insulin protein coated microcrystal (PCMC), a potential candidate for pulmonary drug delivery and commercial insulin was determined on a Danish Myo Tech P110 pressure myograph system. 12 week old Mesenteric resistance arteries from Male Wistar rats were isolated and immersed in a physiological salt solution (PSS) and attached to 2 opposing hollow glass micro-cannula (outer diameter 80 microns). The PSS was gradually warmed to 37°C (at a pressure less than 5mm Hg) for 1hr. Subsequently the pressure was increased up to 40mm Hg over a period 15 minutes and equilibrated for a further 15 minutes after gassing with 95%O2 / 5%CO2 to achieve a pH of 7.4 at 37°C. After normalisation by two washes of 123mM KCl and exposure to 1-10mM noradrenaline the arteries were exposed intraluminally to each insulin preparation by gradual infusion directly into the lumen via a fetal microcannulae inserted to the tip of the glass mounting cannula, at a constant pressure. Results: The preliminary results (full cummulative response curve yet to be determined) demonstrate insulin mediated relaxation to noradrenaline preconstriction. The level of constriction drops from 100% to 42% as the concentration of insulin increases from -11 to -9 Log M for the PCMC compared with a drop from 100 % to 65% for the commercial insulin preparation. However the more potent vasodilatory effect found for the insulin PCMC is more likely to be a result of variance introduced in each dilution step than a real increase in potency. Conclusion: The perfusion bioassay technique provides an excellent method of measuring insulin bioactivity and indicates the insulin loaded on the microcrystal support is fully active

Microstructural evolution of silicate immiscible liquids in ferrobasalts

Abstract: An experimental study of the microstructural evolution of an immiscible basaltic emulsion shows that the Fe-rich liquid forms homogeneously nucleated droplets dispersed in a continuous Si-rich liquid, together with droplets heterogeneously nucleated on plagioclase, magnetite, and pyroxene. Heterogeneous nucleation is likely promoted by localised compositional heterogeneities around growing crystals. The wetting angle of Fe-rich droplets on both plagioclase and magnetite increases with decreasing temperature. Droplet coarsening occurs by a combination of diffusion-controlled growth and Ostwald ripening, with an insignificant contribution from coalescence. Characteristic microstructures resulting from the interaction of immiscible Fe-rich liquid with crystal grains during crystal growth can potentially be used as an indicator of liquid unmixing in fully crystallised natural samples. In magma bodies < ~ 10 m in size, gravitationally driven segregation of immiscible Fe-rich droplets is unlikely to be significant

In-lab three-dimensional printing:an inexpensive tool for experimentation and visualization for the field of organogenesis

The development of the microscope in 1590 by Zacharias Janssenby and Hans Lippershey gave the world a new way of visualizing details of morphogenesis and development. More recent improvements in this technology including confocal microscopy, scanning electron microscopy (SEM) and optical projection tomography (OPT) have enhanced the quality of the resultant image. These technologies also allow a representation to be made of a developing tissue’s three-dimensional (3-D) form. With all these techniques however, the image is delivered on a flat two-dimensional (2-D) screen. 3-D printing represents an exciting potential to reproduce the image not simply on a flat screen, but in a physical, palpable three-dimensional structure. Here we explore the scope that this holds for exploring and interacting with the structure of a developing organ in an entirely novel way. As well as being useful for visualization, 3-D printers are capable of rapidly and cost-effectively producing custom-made structures for use within the laboratory. We here describe the advantages of producing hardware for a tissue culture system using an inexpensive in-lab printer

A versatile scanning method for volumetric measurements of velocity and density fields

Understanding turbulence in a stratified environment requires a detailed picture of both the velocity field and the density field. Experimentally, this represents a significant measurement challenge, especially when full three-dimensional data is needed to accurately characterise the turbulent fields. This paper presents a new approach to obtaining such data through well-resolved, near-instantaneous volume-spanning measurements. This is accomplished using a simultaneous PIV and PLIF scanning setup that is highly versatile while allowing precise overlapping light sheets in a volume. Moreover, the approach detailed here allows for complex scan sequences over varying volumes without the need for mechanical adjustment. To demonstrate the technique, preliminary results from the buoyancy-driven exchange flow through density fluids are shown.This work was supported by EPSRC Programme Grant EP/K034529/1