The Government of Thailand decided recently to introduce a legal system for the protection of plant variety right (PVR) in order to meet its commitment under the TRIPs agreement (part of the WTO agreement) to protect new varieties of plants. Having taken this significant decision - although in reality the decision was probably little more than a formality because of the TRIPs commitment - the government must assess the likely impact of PVR on public and private interests in Thailand and, in the light of that assessment, construct a PVR system suited to the country's particular needs (so far as these can be envisaged). The likely impact of the government's decision and the choice to be made constitute the backbone of this thesis as well as its prime focus. A PVR system is intended primarily to promote invention and innovation in the field of plant breeding. Whether the availability of PVR in Thailand will achieve those objectives cannot be said at this point. Studies carried out in countries with mature PVR systems claim, despite the lack of any solid evidence on which to found the claims, that PVR systems have certain positive or beneficial effects, for example more varieties giving higher yields and better adapted to growing conditions. On the other hand, some commentators believe that these benefits result from other factors, in particular technological advances (for example, improvements in cultivation and management of commercial crops). This thesis concludes that the availability or grant of PVR in Thailand will not have any radical impact on public and private interests there. At present, plant breeding and seed production are carried out by public and private sectors. Available data on seed production and consumption indicate the need for more investment in plant breeding and seed production, particularly in the private sector. A PVR system is unlikely to encourage breeders or producers to invest more because the availability of PVR is not a vital determinant in investment decisions. Fortunately. as far as can be seen at present, a PVR system is unlikely to have negative effects, e. g. seed price rises, obstacles to technological development or environmental dangers. In considering the most appropriate system, the major factors to be assessed are economic impact, existing political commitment, and practicality. The government should adopt the system established by the 1978 UPOV Convention, in preference to the 1991 Convention, because the earlier Convention is the more appropriate for Thailand's developmental needs.

We can view quiver representations of a fixed dimension vector as an algebraic variety over an algebraically closed field $K$. There is an action of the product of general linear groups on each of these varieties where the orbits of the action correspond to isomorphism classes of quiver representation. A $K$-algebra $A$ is said to have the dense orbit property if for each dimension vector, the product of the general linear group acts on each irreducible component of the module variety with a dense orbit. Under certain conditions, a $K$ algebra $A$ is representation finite if and only if it $A$ has the dense orbit property. The implication representation finite implies the dense orbit property is always true. The converse is not true in general, as shown by Chindris, Kinser, and Weyman in \cite{ryan}. Our main theorem of this thesis builds on their work to give a family of representation infinite algebras with the dense orbit property. We also give a conjectured classification of indecomposables with dense orbits. \par In the future, we hope the work presented here can be used to find even more examples of representation infinite algebra with the dense orbit property to then develop deeper theory to classify algebras with the dense orbit property that are representation infinite.

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We consider the pair of a smooth complex projective variety together with an anti-canonical simple normal crossing divisor (we call it "log Calabi- Yau"). Standard examples are toric varieties together with their toric boundaries (we call them "toric pairs"). We provide a numerical criterion for a general log Calabi-Yau to be toric by an inequality between its dimension, Picard number and the number of boundary components. The problem originates in birational geometry and our proof is constructive, motivated by mirror symmetry. / text

We compute the E-polynomials of a family of twisted character varieties M [superscript g] (Sl [subscript n]) by proving they have polynomial count, and applying a result of N. Katz on the counting functions. To compute the number of F [subscript q]-points of these varieties as a function of q, we used a formula of Frobenius. Our calculations made use of the character tables of Gl [subscript n](q) and Sl subscript n](q), previously computed by J. A. Green and G. Lehrer, and a result of Hanlon on the Möbius function of a subposet of set-partitions. The Euler Characteristics of the M [superscript g] (Sl [subscript n]) are calculated then with these polynomial. / text

In this thesis we investigate the problem of defining an extension of sutured instanton Floer homology to give an instanton invariant for a tangle. We do this in three separate steps. First, we investigate the representation variety of singular flat connections on a punctured Riemann surface \(\Sigma\). Suppose \(\Sigma\) has genus \(g\) and that there are \(n\) punctures. We give formulae for the Betti numbers of the space \(\mathcal{R}_{g,n}\) of flat \(SU(2)\)-connections on \(\Sigma\) with trace 0 holonomy around the punctures. By using a natural extension of the Atiyah-Bott generators for the cohomology ring \(H^*(\mathcal{R}_{g,n})\), we are able to write down a presentation for this ring in the case \(g=0\) of a punctured sphere. This is accomplished by studying the intersections of Poincaré dual submanifolds for the new generators and reducing the calculation to a linear algebra problem involving the symplectic volumes of the representation variety. We then study the related problem of computing the instanton Floer homology for a product link in a product 3-manifold <p>\((Y_g, K_n) := (S^1 \times \Sigma, S^1 \times \{n pts\})\).<\p> It is easy to see that the Floer homology of this pair, as a vector space, is essentially the same as the cohomology of \(\mathcal{R}_{g,n}\), and so we set ourselves to determining a presentation for the natural algebra structure on it in the case \(g = 0\). By leveraging a stable parabolic bundles calculation for \(n = 3\) and an easier version of this Floer homology, \(I _*(Y_0, K_n, u)\), we are able to write down a complete presentation for the Floer homology \(I _*(Y_0, K_n)\) as a ring. We recapitulate somewhat the techniques in \([\boldsymbol{27}]\) in order to do this. Crucially, we deduce that the eigenspace for the top eigenvalue for a natural operator \(\mu^{ orb} (\Sigma)\) on \(I_* (Y_0, K_n)\) is 1-dimensional.Finally, we leverage this 1-dimensional eigenspace to define an instanton tangle invariant THI and several variants by mimicking the de nition of sutured Floer homology SHI in \([\boldsymbol{22}]\). We then prove this invariant enjoys nice properties with respect to concatenation, and prove a nontriviality result which shows that it detects the product tangle in certain cases. / Mathematics

This dissertation concerns the study of canonical components of the SL(2, C) character varieties of hyperbolic 3-manifolds. Although character varieties have proven to be a useful tool in studying hyperbolic 3-manifolds, very little is known about their structure. Chapter 1 provides background on this subject. Chapter 2 is dedicated to the canonical component of the Whitehead link. We provide a projective model and show that this model is isomorphic to P^2 blown up at 10 points. The Whitehead link can be realized as 1/1 Dehn surgery on one cusp of both the Borromean rings and the 3-chain link. In Chapter 3 we examine the canonical components for the two families of hyperbolic link complements obtained by 1/n Dehn filling on one component of both the Borromean rings and the 3-chain link. These examples extend the work of Macasieb, Petersen and van Luijk who have studied the character varieties associated to the twist knot complements. We conjecture that the canonical components for the links obtained by 1/n Dehn filling on one component of the 3-chain link are all rational surfaces isomorphic to P^2 blown up at 9n + 1 points. A major goal is to understand how the algebro-geometric structure of these varieties reflects the topological structure of the associated manifolds. At the end of Chapter 3 we discuss common features of these examples and explain how our results lend insight into the affect Dehn surgery has on the character variety. We conclude, in Chapter 4, with a description of possible directions for future research. / text

One of the challenges that Caribbean immigrant parents and children face as they settle into their new environment is interacting with teachers using their variety of English. This study seeks to explore the experiences of Caribbean immigrant parents and their children in their interactions with teachers in Toronto and the perceptions that they have about these interactions. The author’s purpose is to bring voice to their language encounters. Qualitative analysis is utilized throughout the general discussion of the study. Using Colaizzi’s (1978) phenomenology approach, data was collected through semi-structured interviews from a sample of six immigrant parents and seven children within Toronto. The central themes that emerge from the data are organized under the four research questions. The results of the research may assist policy makers, educators, teachers, and support staff who plan and implement programs geared towards enhancing the interaction between themselves and Caribbean immigrant students and parents.