K-theoretic matching of brane charges in S- and U-duality

We discuss K-theoretic matching of D-brane charges in the string duality between type I on the 4-torus and type IIA on a K3 surface. This case is more complex than the familiar case of IIA/IIB duality, which is already well understood, but it turns out that replacing K3 by its orbifold blow-down seems largely to resolve the apparent problems with the theory. In particular, this allows for precise matching of 2-torsion brane charges.Comment: 23 pages. Added more references and discussion, and corrected a minor error in spectral sequence argument in section 3. (Results unaffected.

K-theoretic Aspects of String Theory Dualities

String theory is a a physical field theory in which point particles are replaced by 1-manifolds propagating in time, called strings. The 2-manifold representing the time evolution of a string is called the string worldsheet. Strings can be either closed (meaning their worldsheets are closed surfaces) or open (meaning their worldsheets have boundary). A D-brane is a submanifold of the spacetime manifold on which string endpoints are constrained to lie. There are five different string theories that have supersymmetry, and they are all related by various dualities. This dissertation will review how D-branes are classified by K-theory. We will then explore the $K$-theoretic aspects of a hypothesized duality between the type I theory compactified on a 4-torus and the type IIA theory compactified on a K3 surface, by looking at a certain blow down of the singular limit of K3. This dissertation concludes by classifying D-branes on the type II orientifold T4/Z2 when the Z2 action is multiplication by -1 and the H-flux is trivial. We find that classifying D-branes on the singular limit of K3, T4/Z2 by equivariant K-theory agrees with the classification of D-branes on a smooth K3 surface by ordinary K-theory

Multi-objective hull-form optimization of a swath configuration via design-space dimensionality reduction, multi-fidelity metamodels, and swarm intelligence

A multi-objective simulation-based design optimization (SBDO) is presented for the resistance reduction and displacement increase of a small water-plane area twin hull (SWATH). The geometry is realized as a parametric model with the CAESESQR software, using 27 design parameters. Sobol sampling is used to realize design variations of the original geometry and provide data to the design-space dimensionality reduction method by Karhunen-Lo`eve expan- sion. The hydrodynamic performance is evaluated with the potential flow code WARP, which is used to train a multi-fidelity metamodel through an adaptive sampling procedure based on prediction uncertainty. Two fidelity levels are used varying the computational grid. Finally, the SWATH is optimized by a multi-objective deterministic version of the particle swarm optimiza- tion algorithm. The current SBDO procedure allows for the reduction of the design parameters from 27 to 4, resolving more than the 95% of the original geometric variability. The metamodel is trained by 117 coarse-grid and 27 fine-grid simulations. Finally, significant improvements are identified by the multi-objective algorithm, for both the total resistance and the displacement

Acute hyperkalaemia in a captive Persian leopard (Panthera pardus saxicolor) immobilised with a ketamine-medetomidine combination

A 12-year-old captive male Persian leopard (Panthera pardus saxicolor) required general anaesthesia for examination and treatment of a recurrent oral fistula. Medetomidine (0.065 mg/kg) and ketamine (3.6 mg/kg) administered intramuscularly by blowpipe darting effectively immobilised the animal that was maintained under general anaesthesia with inhaled isoflurane. In absence of clinical signs, acute hyperkalaemia (7.26 mmol/l) was incidentally recognised by the end of anaesthesia. Factors that might have played a role in hyperkalaemia development, such as the use of α2-adrenoceptor agonists, stress response, acidosis or dopamine administration, are discussed. Hyperkalaemia should be considered as a potential complication while anaesthetising large non-domestic felids