High-output congestive heart failure following transjugular intrahepatic portal-systemic shunting

A hyperdynamic circulatory state with elevated cardiac output, decreased peripheral vascular resistance, and sodium retention occurs in patients with portal cirrhosis. Surgical portal-systemic shunts and transjugular intrahepatic portal-systemic shunts (TIPS) have been shown to worsen the high-output state in these patients. However, clinical evidence of high-output congestive heart failure has been reported only rarely to complicate cirrhosis. We describe a patient who developed high-output congestive heart failure with markedly elevated filling pressures after TIPS and had complete resolution of heart failure after liver transplantation.     

Stock trading strategy creation using GP on GPU

This paper investigates the speed improvements available when using a graphics processing unit (GPU) for evaluation of individuals in a genetic programming (GP) environment. An existing GP system is modified to enable parallel evaluation of individuals on a GPU device. Several issues related to implementing GP on GPU are discussed, including how to perform tree-based GP on a device without recursion support, as well as the effect that proper memory layout can have on speed increases when using CUDA-enabled nVidia GPU devices. The specific GP implementation is designed to evolve stock trading strategies using technical analysis indicators. The second goal of this research is to investigate the possible improvement in performance when training individuals on a larger number of stocks and training days. This increased training size (nearly 100,000 training points) is enabled due to the speedups realized by GPU evaluation. Several different scenarios were used to test various speed optimizations of GP evaluation on the GPU device, with a peak speedup factor of over 600 (when compared to sequential evaluation on a 2.4 GHz CPU). Also, it is found that increasing the number of stocks and the length of the training period can result in higher out-of-training testing profitability.     

Fourth International Conference on Durability of Building Materials and Components

RILEM Bulletin

Fourth International Conference on Durability of Building Materials and Components     

Analytical electron microscopy of Al2O3 implanted with iron ions

Single crystals of -Al₂O₃ were implanted with iron ions at room temperature to fluences ranging from 4×10¹⁶ Fe cm^–2 to 1×10¹⁷ Fe cm^–2. The microstructure and composition in the implanted region were examined using analytical electron microscopy techniques. Special emphasis was placed on monitoring the microstructural changes which take place during post-implantation annealing. Clusters of metallic -Fe were identified in the specimen after implantation to a dose of 1×10¹⁷ Fe cm^–2. Analytical electron microscopy of implanted specimens annealed in oxygen revealed the redistribution of the implanted iron and the formation of surface precipitates of -Fe₂O₃, subsurface precipitates of various forms of spinel, and, in some cases, subsurface precipitates of iron, depending on the annealing temperature. Examination of implanted specimens annealed under reducing conditions revealed the presence of precipitates of -Fe.     

Practical observations on the methodology for determining 3-methyl-l-histidine using fluorescamine derivatives

The method for the detection and possible quantification of the unusual amino acid 3-methyl-l-histidine has been refined and elucidated. This is an essential prerequisite for the determination of its value as a robust unequivocal index of lean meat protein.     

On the layer removal analysis of residual stress

The layer removal analysis of residual stress distribution is examined for mouldings which contain depth-varying Young's modulus. The approach is to compute the stress distribution which would be derived from the layer removal procedure if the assumption is made that the Young's modulus is uniform, and to compare it with the actual stress distribution. For this analysis a parabolic stress distribution is assumed to be present, and computed distributions are obtained for two cases, (i) in which the modulus varies linearly from the surface to the centre of the moulding and (ii) in which the modulus has a constant value near to the surface (skin) then changes suddenly to another constant value in the interior (core). The general features of the computed profiles are compared with experimental layer removal analyses conducted on injection-moulded specimens and the extent to which non-uniform modulus influences the results of such studies is discussed.     

Development of materials specifications and emplacement procedures for backfilling nuclear fuel waste vaults

Atomic Energy of Canada Limited and Ontario Hydro are conducting a research program to assess the environmental impact and safety of the concept of disposal of nuclear fuel waste in an underground vault in plutonic rock of the Canadian Shield. The Vault Sealing Program, one of the components of the Nuclear Fuel Waste Management Program, is concerned with the development of materials specifications and emplacement procedures for backfilling the vault. Backfilling materials would surround the nuclear waste containers and fill all vault openings to minimize leaching and movement of radionuclides. This paper presents the procedure followed to select candidate backfill materials, the integration of mathematical modelling studies and physical testing for the definition of materials specifications, and the principal elements of the recommended handling and emplacement systems.     

Utility,probabilistic constraints,mean and variance of discounted rewards in Markov decision processes

Summary This paper deals with discounted Markov decision processes, Markov with respect to a finite statespaceI, where for eachiI, and each decision epocht, there is a finite action space K(i, t). The paper is concerned with problems which are formulated in terms of the discounted rewards in several ways. In order to ensure that optimal, or near optimal, policies are obtained, the state spaceI is extended to augmented state-spaces A(n), or A(), including the accumulated discounted rewards. Specimen problems are formulated and some computational aspects examined.

---

Zusammenfassung Es werden diskontierte Markovsche Entscheidungsprozesse behandelt mit endlichem Zustandsraum I, wobei die Mengen der zulässigen Entscheidungen K(i, t) vom Zustandi I und vom Zeitpunktt abhängen können. Es werden verschiedene Zielfunktionen betrachtet, die jeweils als Funktion des diskontierten Gesamtgewinns (nicht dessen Erwartungswerts) formuliert werden. Um optimale oder fast-optimale Politiken zu erhalten ohne die gesamte Vorgeschichte zu registrieren, wird der Zustandsraum um die akkumulierten diskontierten Auszahlungen erweitert. Eine Auswahl solcher Probleme wird exemplarisch diskutiert einschließlich einiger Aspekte der numerischen Behandlung.

     

Reward revision and the average reward markov decision process

Summary We integrate two numerical procedures for solving the average reward Markov decision process (MDP), standard successive approximations and modified policy iteration with reward revision. Reward revision is the process of revising the reward structure of a second, more computationally desirable MDP so as to produce, in the limit, an optimality equation having a fixed point identical to that associated with the original MDP. A numerical study indicates that for MDP's having a non-sparse transition structure with a small number of relatively large entries per row, the addition of reward revision can have significant computational benefits.

---

Zusammenfassung Zur Lösung Markovscher Entscheidungsprozesse (MDP) mit Durchschnitts-Kriterium werden zwei numerische Verfahren, nämlich sukzessive Approximation und modifizierte Politik-Iteration, mit einer Transformation, der sogenannten 'Reward-Revision, kombiniert. Bei dieser Transformation werden die Übergangswahrscheinlichkeiten so abgeändert (ausgedünnt), daß das neue Modell sich numerisch günstiger verhält. Dazu müssen die einstufigen Erträge so revidiert werden, daß die Optimalitäts-Gleichung des neuen Modells im Limes mit der des ursprünglichen übereinstimmt. Numerische Untersuchungen zeigen, daß für MDP mit stark besetzten Übergangsmatrizen, bei denen nur an wenigen Stellen je Zeile große Werte stehen, die Anwendung von 'Reward Revision zu wesentlichen Einsparungen an Rechenaufwand führen kann.

---

---

Research supported by NSF Grant ECS-8319355