Discovery of Frequent Episodes in Event Sequences

Sequences of events describing the behavior and actions of users or systems can be collected in several domains. An episode is a collection of events that occur relatively close to each other in a given partial order. We consider the problem of discovering frequently occurring episodes in a sequence. Once such episodes are known, one can produce rules for describing or predicting the behavior of the sequence. We give efficient algorithms for the discovery of all frequent episodes from a given class of episodes, and present detailed experimental results. The methods are in use in telecommunication alarm management.     

Species number, historical elements and protection of threatened species in the flora of Helsinki, Finland

Recent urban ecological research shows high species numbers in slowly developed cities and towns. Urban development is known to fragment, change and weaken urban biodiversity. Conservation areas have been the main tool in protecting threatened species both in rural and urban municipalities in Finland. However, very little is known about how successful conservation areas are in protecting rare and threatened species and their habitats in boreal cities and towns. Helsinki, the capital of Finland, is a rapidly urbanising hemiboreal city, which has a high number of vascular plant species in both native and urban biotopes. One and 0.25 km² grid square maps and simple overlay methods are being used to analyse data on species occurrence and land use. Total species number, a rarity index and historical and threatened groupings are used to classify species and their habitats. At present, conservation areas can protect only a small proportion of threatened species in Helsinki. More protection areas, green areas in future land-use decisions and new management goals are needed to protect the biodiversity of existing vascular plant species.     

External quicksort

An external sorting algorithm based on quicksort is presented. The file to be sorted is kept on a disk and only those blocks are fetched into the main memory which are currently needed. At each time, a block is kept in the main memory, if the expected space-time cost of holding it until its next use is smaller than the expected space-time cost of removing it and fetching it again. The efficiency of the algorithm is tested through simulation experiments and the results are compared to those achieved with mergesort in a corresponding environment. The total execution time and the main memory space-time integral are used for measuring the performance.

When equal block sizes are used, external quicksort results in a much smaller average space requirement than mergesort. On the other hand, mergesort is somewhat faster than external quicksort. The main memory space-time integral of quicksort is always considerably smaller than that of mergesort. External quicksort is less sensitive to the block size and to the file size. With faster disks, the performance of external quicksort improves faster than that of mergesort. The relative difference of the algorithms is independent of the file size.

The external quicksort is also analytically compared to some previous external versions of quicksort. It is shown to be satisfied with less space and fewer block fetches than the others.     

MEASUREMENT OF PRIMARY- AND SECONDARY-MINIMUM COAGULATION RATES IN COLLOIDAL DISPERSIONS

Particle interaction theory cannot completely explain observed phenomena when particles interact in the vicinity of the secondary minimum. No convenient experimental techniques to probe the secondary minimum are currently available. A technique based on the use of hydrodynamic shear to disrupt secondary-minimum bonds is discussed for this purpose. The use off this procedure is justified in terms of a relative particle trajectory analysis. An experimental apparatus was constructed to utilize this methodology.     

What is project governance and what are its origins?

Although there is an ever-increasing discussion on governance in recent project research, the concept of project governance and its main origins remains ambiguous. In this paper, we examine project governance literature and contrast it to general governance literature published outside the domain of project research. Our analysis revealed the existence of two distinct and relatively independent streams of research. One of these streams addresses project governance as a phenomenon external to any specific project, while the other views project governance as internal to a specific project. Our results further indicate that while project governance literature bases most of its argumentation on established project research it also, to a significant extent, draws from the transaction cost economics literature. Based on our findings, we argue that there exists considerable potential for bridging project governance literature and general governance literature further.     

Project governance and path creation in the early stages of Finnish nuclear power projects

In this paper we focus on the early stages of projects and their governance implications by investigating the introduction of nuclear power in Finland. We look at the early stages through the lens of path dependence and illustrate how early decisions may lead the project down the wrong path. However, we also develop a path creation perspective in order to develop an understanding of how the project actors in our case deliberately navigated in the cold war atmosphere to avoid a budding lock-in. This historical study highlights the importance of building relationships between key actors and securing their commitment during the early stages of a project. We argue that strong relationships and commitment open up opportunities for creating alternative paths during project appraisal, increase the array of available governance mechanisms, and hence lay the foundations for the final governance structure of the project execution phase.     

Supplier capabilities in large shipbuilding projects

Project-based firms concentrate on their core capabilities outsourcing non-core activities. As project contractors increasingly use external suppliers to complement their own capability base, the importance of supplier selection is emphasized. Supplier choices should rely on accurate knowledge of the suppliers' capabilities. We examine the literature related TO supplier capabilities in collaborative, discontinuous project business. We use a qualitative, embedded single-case strategy in shipbuilding industry to explore the importance of supplier capabilities in one shipyard and examine how consistently the shipyard and its 20 suppliers assess the capabilities of the suppliers. Our results show that the buyer prioritizes technical, operational and business capabilities over relational and developmental capabilities, and that the buyer and its suppliers diverge in their assessments of the suppliers' capabilities, creating potential misunderstandings and false expectations in the buyer–supplier relationships. We complement prior research by adding a new dimension of business capabilities into the supplier's capability base in the field of project business.     

Segmentation,paging and optimal page sizes in virtual memory

On the basis of empirical data two topics concerning virtual memory systems are discussed: determining an optimal page size and performance of segmentation as compared to paging. Several production programs have been executed (on a simulator) both in a segmented system and in a paged system with various page sizes; the memory management was based on the working set policy. The memory usage and the fault rates were recorded, and the lifetime functions and space-time integrals were evaluated. The observations are explained using a new model of program behaviour which is a refinement of the phase-transition model. The results show that there is no globally optimal page size. Two characteristic types of programs are observed: the first requires a small page size and a large window size, the second requires a large page size and a small window size. Segmentation and paging are compared with respect to their usage of various resources. In the sense of the space-time integral, segmentation usually outperforms paging; if the mean segment size is large, the difference is remarkable. Several commonly used assumptions about the effects of page size on program behaviour are validated; some of them are found inaccurate or even wrong.     

Modification of buffered peptone water for improved recovery of heat-injured Salmonella Typhimurium

Abstract: Rapid detection of Salmonella in foods is often limited by the high demand for the sensitivity of detection, poor physiological conditions of the target cells, and high concentration of background flora. In this study, the conditions of nonselective enrichment cultivation were modified in order to improve the quantitative detection of heat‐injured Salmonella in minced meat. The effect of the modifications on the recovery was observed by means of RNA‐based sandwich hybridization, which was adjusted for the quantification of Salmonella enterica 23S rRNA in crude cell extracts. The supplementation of buffered peptone water with the enzyme‐controlled substrate delivery system EnBase‐Flo^® and ferrioxamine E was shown to improve the recovery of cells in both single strain cultures and in the presence of minced meat. The presented results can be used for the development of more efficient enrichment cultivation media for faster detection of food borne Salmonella.