The diagnosis of transient ischemic attacks

The diagnosis of transient ischemic attack (TIA) is fraught with difficulty, since the diagnosis rests entirely upon the history of the patient's symptoms and the neurologist's skill in questioning the patient. The aim of this thesis is to investigate various measures to improve the reliability in making this diagnosi

Optimal oral anticoagulant therapy in patients with nonrheumatic atrial fibrillation and recent cerebral ischemia

A number of studies have demonstrated the efficacy of oral anticoagulant therapy in reducing the risk of stroke and systemic embolism in patients with nonrheumatic atrial fibrillation. However, both the targeted and the actual levels of anticoagulation differed widely among the studies, and a number of studies failed to report standardized prothrombin-time ratios as international normalized ratios (INRs). We therefore performed an analysis to determine the intensity of oral anticoagulant therapy in nonrheumatic atrial fibrillation that provides the best balance between the prevention of thromboembolism and the occurrence of bleeding complications

A random matrix decimation procedure relating β=2/(r+1)\beta = 2/(r+1) to β=2(r+1)\beta = 2(r+1)

Classical random matrix ensembles with orthogonal symmetry have the property that the joint distribution of every second eigenvalue is equal to that of a classical random matrix ensemble with symplectic symmetry. These results are shown to be the case $r=1$ of a family of inter-relations between eigenvalue probability density functions for generalizations of the classical random matrix ensembles referred to as $\beta$-ensembles. The inter-relations give that the joint distribution of every $(r+1)$-st eigenvalue in certain $\beta$-ensembles with $\beta = 2/(r+1)$ is equal to that of another $\beta$-ensemble with $\beta = 2(r+1)$. The proof requires generalizing a conditional probability density function due to Dixon and Anderson.Comment: 19 pages, 1 figur

Migration with local public goods and the gains from changing places

Without public goods and under fairly standard assumptions, in Hammond and Sempere (J Pub Econ Theory, 8: 145–170, 2006) we show that freeing migration enhances the potential Pareto gains from free trade. Here, we present a generalization allowing local public goods subject to congestion. Unlike the standard literature on fiscal externalities, our result relies on fixing both local public goods and congestion levels at their status quo values. This allows constrained efficient and potentially Pareto improving population exchanges regulated only through appropriate residence charges, which can be regarded as Pigouvian congestion taxes

On non-permutation solutions to some two machine flow shop scheduling problems

In this paper, we study two versions of the two machine flow shop scheduling problem, where schedule length is to be minimized. First, we consider the two machine flow shop with setup, processing, and removal times separated. It is shown that an optimal solution need not be a permutation schedule, and that the problem is NP-hard in the strong sense, which contradicts some known results. The tight worst-case bound for an optimal permutation solution in proportion to a global optimal solution is shown to be 3/2. An O(n) approximation algorithm with this bound is presented. Secondly, we consider the two machine flow shop with finite storage capacity. Again, it is shown that there may not exist an optimal solution that is a permutation schedule, and that the problem is NP-hard in the strong sense

The Social Shaping of the early Dutch Management Schools - Professions and the power of Abstraction

In this paper we provide an alternative explanation for the rise of modern management schools at the turn of the 20th century. We argue that these schools were not just responses of the higher education system to the demand of industrializing companies for a new class of professional managers, like Chandler suggests. Based on our historical research we found that the struggle for emancipation of the new professions (engineers and accountants) was the main driver for the founding of these schools. Management schools were viewed as the main vehicles to raise the social status of these new professions. To legitimize their position in the higher education system, abstraction appeared to be the dominant strategy of the professions. By abstraction they could distinguish themselves from the lay public and other professional groups in the domain of management. At the moment the new professions had a foot in the higher education system the engineers and the accountants contested for the new management domain. Abstraction appeared also the successful strategy of the accountants to distinguish themselves from the engineers and to establish a sound base for the development of the Dutch variant of business economics

Symmetrized models of last passage percolation and non-intersecting lattice paths

It has been shown that the last passage time in certain symmetrized models of directed percolation can be written in terms of averages over random matrices from the classical groups $U(l)$, $Sp(2l)$ and $O(l)$. We present a theory of such results based on non-intersecting lattice paths, and integration techniques familiar from the theory of random matrices. Detailed derivations of probabilities relating to two further symmetrizations are also given.Comment: 21 pages, 5 figure