Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2008. / Includes bibliographical references. Also available in electronic version.

In this thesis, I study the local employment multiplier effect; the effect of employment in the tradable sector on employment in the non-tradable sector of the same region. Using a reduced form regression with a shift-share instrument I find a significant local multiplier effect in Metropolitan Statistical Areas in the USA. I show that this result is robust to many different regional definitions, controls and ways of classifying tradable industries. I find larger multipliers for high-wage or high-skilled workers in the tradable sector and I find that most of the jobs created in the non-tradable sector are fulfilled by high-skilled workers who already reside in the region. A replication of the most influential paper in this literature, by Moretti (AER; 2010), demonstrates the sensitivity of his results to six idiosyncrasies of his analysis. To better understand how these local multipliers work, I develop an efficiency wage model with rural-urban migration for the non-tradable sector. In this model, I consider the impact of a shock to employment in the tradable sector in the city and find a positive local employment multiplier effect. The model predicts that attracting tradable jobs to a city has a bigger positive impact on employment in the non-tradable sector in the same city when the unemployment rate is higher. The model also predicts that this increase is driven by a larger multiplier for current inhabitants and that there is no, or even a negative, effect of the unemployment rate on the multiplier for movers. Both these predictions are reflected in the results of my non-parametric analysis of the data. I find similar results for European TL3 regions. Policies that try to increase growth in less favoured regions by stimulating tradable firms to locate in areas with high unemployment, will both reduce disparities between regions and efficiently reduce unemployment across the board.

This thesis is motivated by the problem of understanding the endpoint mapping properties of higher-dimensional Marcinkiewicz multipliers. The one-dimensional case was definitively characterised by Tao and Wright. In particular, they proved that Marcinkiewicz multipliers acting on functions over the real line map the Hardy space H¹(ℝ) to L¹;∞(ℝ) and they locally map L log¹/² L to L¹;∞ and that these results are sharp. The classical inequalities of Paley and Zygmund involving lacunary sequences can be regarded as rudimentary prototypes of the aforementioned results of Tao and Wright on the behaviour of Marcinkiewicz multipliers "near" L¹(ℝ). Motivated by this fact, in Chapter 3 we obtain higher-dimensional variants of these two inequalities and we establish sharp multiplier inclusion theorems on the torus and on the real line. In Chapter 4 we extend the multiplier inclusion theorem on T of Chapter 3 to higher dimensions. In the last chapter of this thesis, we study endpoint mapping properties of the classical Littlewood-Paley square function which can essentially be regarded as a model Marcinkiewicz multiplier. More specifically, we give a new proof to a theorem due to Bourgain on the growth of the operator norm of the Littlewood- Paley square function as p → 1+ and then extend this result to higher dimensions. We also obtain sharp weak-type inequalities for the multi-parameter Littlewood- Paley square function and prove that the two-parameter Littlewood-Paley square function does not map the product Hardy space H¹ to L¹;∞.

No description available.

No description available.

No description available.

The distance to uncontrollability of a controllable linear system is a measure of the degree of perturbation a system can undergo and remain controllable. The definition of the distance to uncontrollability leads to a non-convex optimization problem in two variables. In 2000 Gu proposed the first polynomial time algorithm to compute this distance. This algorithm relies heavily on efficient eigenvalue solvers. In this work we examine two alternative algorithms that result in linear matrix inequalities. For the first algorithm, proposed by Ebihara et. al., a semidefinite programming problem is derived via the Kalman-Yakubovich-Popov (KYP) lemma. The dual formulation is also considered and leads to rank conditions for exactness verification of the approximation. For the second algorithm, by Dumitrescu, Şicleru and Ştefan, a semidefinite programming problem is derived using a sum-of-squares relaxation of an associated matrix-polynomial and the associated Gram matrix parameterization. In both cases the optimization problems are solved using primal-dual-interior point methods that retain positive semidefiniteness at each iteration. Numerical results are presented to compare the three algorithms for a number of benchmark examples. In addition, we also consider a system that results from a finite element discretization of the one-dimensional advection-diffusion equation. Here our objective is to test these algorithms for larger problems that originate in PDE-control. / Master of Science

Na primeira parte desta tese nós estudamos os operadores de convolução Tµ que são tauberianos agindo nas álgebras de grupo L1(G), onde G é um grupo abeliano localmente compacto e µ é uma medida de Borel complexa sobre G. Nós mostramos que esses operadores são invertíveis se o grupo G não é compacto e que eles são de Fredholm quando têm imagem fechada e G é compacto. Além disso, se G é compacto nós provamos que Tµ é de Fredholm se a parte singular contínua de µ respeito à medida de Haar de G é zero. Na segunda parte nós estudamos os operadores de convolução Tµ que são cotauberianos em L1(G). Nós mostramos que esses operadores são tauberianos e são de Fredholm (de índice zero). Além disso, mostramos que Tµ é tauberiano se, e somente se, sua extensão natural à álgebra de medidas M(G) é tauberiano. Mostramos alguns resultados obtidos por dualidade de espaços de Banach para os operadores de convolução tauberianos e cotauberianos agindo sobre C0(G), o espaço de Banach das funções complexas que se anulam no infinito, e L&#8734(G), o espaço de Banach das funções mensuráveis essencialmente limitadas. Finalmente estendemos alguns dos resultados obtidos para álgebras de Banach que possuem uma identidade aproximada limitada. / In the first part of this thesis we study the convolution operators Tµwhich are tauberian as operators acting on the group algebras L1(G), where G is a locally compact abelian group and µ is a complex Borel measure on G. We show that these operators are invertible when G is non-compact, and that they are Fredholm when they have closed range and G is compact. Moreover, if G is compact, we prove that Tµ is Fredholm when the singular continuous part of µ with respect to the Haar measure on G is zero. In the second part we study the convolution operators Tµ which are cotauberian as operators acting on L1(G). We show that these operators are tauberian and Fredholm of index zero. Moreover, we show that Tµ is tauberian as an operator on L1(G) if and only if so is its natural extension to the algebra of measures M(G). We show some results, obtained by duality, about tauberian and cotauberian convolution operators on the Banach spaces L&#8734(G) of equivalence classes of essentially bounded mesurable functions on Gand C0(G) of complex valued continuous functions on Gwhich vanish at infinity. Finally, we extend some results obtained to Banach algebras with a bounded identity approximate.

by Sin Yu Tsang. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references (leaves 40-42). / Chapter Chapter 1. --- Introduction --- p.1 / Chapter Chapter 2. --- Two-level structural equation model --- p.5 / Chapter Chapter 3. --- Estimation of the model under general constraints --- p.11 / Chapter Chapter 4. --- Estimation of the model under linear constraints --- p.22 / Chapter Chapter 5. --- Simulation results --- p.27 / Chapter 5.1 --- "Artificial examples for ""modified"" EM algorithm" --- p.27 / Chapter 5.2 --- "Artificial examples for ""restricted"" EM algorithm" --- p.34 / Chapter Chapter 6. --- Discussion and conclusion --- p.38 / References --- p.40 / Tables --- p.43

Na primeira parte desta tese nós estudamos os operadores de convolução Tµ que são tauberianos agindo nas álgebras de grupo L1(G), onde G é um grupo abeliano localmente compacto e µ é uma medida de Borel complexa sobre G. Nós mostramos que esses operadores são invertíveis se o grupo G não é compacto e que eles são de Fredholm quando têm imagem fechada e G é compacto. Além disso, se G é compacto nós provamos que Tµ é de Fredholm se a parte singular contínua de µ respeito à medida de Haar de G é zero. Na segunda parte nós estudamos os operadores de convolução Tµ que são cotauberianos em L1(G). Nós mostramos que esses operadores são tauberianos e são de Fredholm (de índice zero). Além disso, mostramos que Tµ é tauberiano se, e somente se, sua extensão natural à álgebra de medidas M(G) é tauberiano. Mostramos alguns resultados obtidos por dualidade de espaços de Banach para os operadores de convolução tauberianos e cotauberianos agindo sobre C0(G), o espaço de Banach das funções complexas que se anulam no infinito, e L&#8734(G), o espaço de Banach das funções mensuráveis essencialmente limitadas. Finalmente estendemos alguns dos resultados obtidos para álgebras de Banach que possuem uma identidade aproximada limitada. / In the first part of this thesis we study the convolution operators Tµwhich are tauberian as operators acting on the group algebras L1(G), where G is a locally compact abelian group and µ is a complex Borel measure on G. We show that these operators are invertible when G is non-compact, and that they are Fredholm when they have closed range and G is compact. Moreover, if G is compact, we prove that Tµ is Fredholm when the singular continuous part of µ with respect to the Haar measure on G is zero. In the second part we study the convolution operators Tµ which are cotauberian as operators acting on L1(G). We show that these operators are tauberian and Fredholm of index zero. Moreover, we show that Tµ is tauberian as an operator on L1(G) if and only if so is its natural extension to the algebra of measures M(G). We show some results, obtained by duality, about tauberian and cotauberian convolution operators on the Banach spaces L&#8734(G) of equivalence classes of essentially bounded mesurable functions on Gand C0(G) of complex valued continuous functions on Gwhich vanish at infinity. Finally, we extend some results obtained to Banach algebras with a bounded identity approximate.