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B-trees have been ubiquitous in database management systems for several decades, and they are used in other storage systems as well. Their basic structure and basic operations are well and widely understood including search, insertion, and deletion. Concurrency control of operations in B-trees, however, is perceived as a difficult subject with many subtleties and special cases. The purpose of this survey is to clarify, simplify, and structure the topic of concurrency control in B-trees by dividing it into two subtopics and exploring each of them in depth. Categories and Subject Descriptors: H.2.4 [Database Management]: Systems--Concurrency; H.3.0 [Information Storage and Retrieval]: General General Terms: Algorithms ACM Reference Format: Graefe, G. 2010. A survey of B-tree locking techniques. ACM Trans. Datab. Syst. 35, 3, Article 16 (July 2010), 26 pages. DOI = 10.1145/1806907.1806908 http://doi.acm.org/10.1145/1806907.1806908

The rapid pace of technological change has caused many competitive challenges for hospitals. The emergence of sophisticated technologies in the health care industry determines the important need for continuous and quick changes in organizational activities. New clinical Information Technology is supposed to improve the quality of health care delivery as an innovation. But it is fully naive if any new technology simply considered as an innovation. New technologies flourish as an innovation if the process of introduction and implementation is managed successfully. Also, if a new technology can change the process of health care delivery, it can emerge as an innovation and provides a competitive advantage for hospitals. Otherwise all the effort and investment are doomed to failure. This research as a conceptual study highlights how new clinical IT systems can contribute to organizational performance in hospitals., INTRODUCTION Managers, policy makers, and researchers have paid much attention to the important role of new technologies and innovations for competitiveness and growth. Yet, all new technologies and innovations don't [...]

Many practitioners and researchers believe that the application of information systems in the construction industry lags behind that of other industries such as the manufacturing industry, because the construction industry is mainly composed of small to medium size companies. Besides, to many people, the value of information systems to their business is vague and elusive. Existing studies on the value of information systems are not specifically focused on small to medium size specialty contractors such as electrical contractors. In addition, with an intention to demonstrate the value of information systems to the improvement of operations or business of all relevant companies, those studies typically do not look into the impact of information systems on the competitive advantage of individual companies. This paper argues that such a generalization of the value of information systems, although valuable to both practitioners and researchers, may have overlooked the fact that the value of information systems needs to be reflected through improved competitive advantage of a company and the competitive advantage is company specific. Thus, the examination of different effects of information systems on individual companies can generate useful insight into the value of information systems because such a strategy leads to a better understanding of the relationships between information systems and the competitive advantage of individual companies. With such a perspective, this study applies a case study strategy to study five small to medium size electrical construction companies based on the resource-based view theory. The case studies show that the observed electrical construction companies are well equipped in terms of physical information infrastructure in relation to their business objectives regardless of company size. However, their capabilities of strategically integrating information systems with their business plans and with their external business partners are general lacking, compared with their physical information system infrastructure. This is partly because many electrical contractors do not fully understand that there are many different forms of information systems that have different impacts on gaining and sustaining competitive advantage. This paper then conjectures that the existing imbalanced application of information systems may not lead to the improved competitive advantage of electrical construction companies, which in turn prevent many contractors from clearly seeing the value of the information systems. Thus, the paper further points out that a plan for the systematical implementation of information systems in a company is very important. However, the successful development of such a plan depends on a better understanding of electrical contactors on the concepts of information system capabilities, competitive advantage, and their relationships. CE Database subject headings: Small business; Construction companies; Information systems; Information management.

This paper describes a new approach for laser bone treatment according to a preoperative plan. The advantages of using laser systems are the free choice of the cutting geometry and the possibility of bone treatment without any severe thermal damage. On the other hand, the control of bone removal depth is difficult. Due to the lack of haptical feedback, it is only possible to control the bone removal visually. In addition, by selecting wrong laser parameters and incorrect handling, the tissue can sustain thermal damage. To solve this problem, an approach of navigated and model-based calculation of depth ablation has been investigated. The focus of this paper was to verify the feasibility of precise and safe laser bone removal by combining navigation information with mathematical and volumetric modeling. For the mathematical modeling, known approaches are used. On the basis of CT data, cavities in a bovine bone were planned with a navigation system. With an optical measurement system, the position of the laser handpiece was calculated relative to the bone. Using a mathematical model, the theoretical cavity depth was calculated for each laser pulse and displayed on the navigation screen. Thereby, the material removal was determined in a volume model. With this information, five cavities were created by the laser using constant energy settings. A final measurement of the cavities' depths showed an error of less than 1 mm. Index Terms--Bone treatment, medical information system, medical laser and medical navigation, medical treatment, power control.

This paper examines the statistical distributions of interarrival and response times for construction-site correspondence. Data from a number of construction projects are analyzed and hypotheses are proposed and tested to link the probability distribution to the type of correspondence. Although the commonly assumed exponential distribution of interarrival times is found to be accurate for all types of correspondence, the response times for different types of correspondence follow different distributions depending on the type of correspondence. In particular, a power law relationship is observed between incidence frequency and response time for requests for information. Knowing the statistical distributions for a class of events helps managers forecast future work and manage risk. Simulation models used by practitioners and researchers for various project management goals are also improved by incorporating appropriate statistical distributions for generating various events. CE Database subject headings: Construction management: Information management: Information systems: Statistics: Simulation models.

A top-k query combines different rankings of the same set of objects and returns the k objects with the highest combined score according to an aggregate function. We bring to light some key observations, which impose two phases that any top-k algorithm, based on sorted accesses, should go through. Based on them, we propose a new algorithm, which is designed to minimize the number of object accesses, the computational cost, and the memory requirements of top-k search with monotone aggregate functions. We provide an analysis for its cost and show that it is always no worse than the baseline "no random accesses" algorithm in terms of computations, accesses, and memory required. As a side contribution, we perform a space analysis, which indicates the memory requirements of top-k algorithms that only perform sorted accesses. For the case, where the required space exceeds the available memory, we propose disk-based variants of our algorithm. We propose and optimize a multiway top-k join operator, with certain advantages over evaluation trees of binary top-k join operators. Finally, we define and study the computation of top-k cubes and the implementation of roll-up and drill-down operations in such cubes. Extensive experiments with synthetic and real data show that, compared to previous techniques, our method accesses fewer objects, while being orders of magnitude faster. Categories and Subject Descriptors: H.2.0 [Database Management]: General; H.3.3 [Information Storage and Retrieval]: Information Search and Retrieval General Terms: Algorithms, Experimentation, Performance Additional Key Words and Phrases: Top-k queries, rank aggregation

ABSTRACT This paper takes a retrospective look over Wal-Mart's IT systems. Major types of IT systems used by Wal-Mart are listed chronologically. The paper then explains the economies of IT […]

This article presents a framework that helps companies utilize data to transform knowledge into business results. Research on data-to-knowledge efforts from over 20 companies reveals the main components of successful knowledge management include strategic planning, recruiting and retaining talented employees, developing a data-oriented organizational culture, and structuring analytic resources.

The Virtual Design Team (VDT) extends and operationalizes Galbraith's (1973) information-processing view of organizations. VDT simulates the micro-level information processing, communication, and coordination behavior of participants in a project organization and predicts several measures of participant and project-level performance. VDT-1 (Cohen 1991) and VDT-2 (Christiansen 1993) modeled project organizations containing actors with perfectly congruent goals engaged in complex but routine engineering design work within static organization structures. VDT-3 extends the VDT-2 work process representation to include measures of activity flexibility, complexity, uncertainty, and interdependence strength, It explicitly models the effects of goal incongruency between agents on their information processing and communication behavior while executing more flexible tasks. These extensions allow VDT to model more flexible organizations executing less routine work processes. VDT thus bridges rigorously between cognitive and social psychological micro-organization theory and sociological and economic macro-organization theory for project teams. VDT-3 has been used to model and simulate the design of two major subsystems of a complex satellite launch vehicle. This case study provides initial evidence that the micro-contingency theory embodied in VDT-3 can be used to predict organizational breakdowns, and to evaluate alternative organizational changes to mitigate identified risks. VDT thus supports true 'organizational engineering' for project teams. Keywords: Agency Theory; Concurrent Engineering; Coordination Theory; Contingency Theory; Goal Incongruency; Interdependence; Project Management; Project Organizations; Computational Organizational Design; Information Processing; New Product Development; Organization Design; Professionals; Semiroutine Tasks

Issues discussed concern data mining techniques to gather meaningful knowledge from databases that store DNA-related information. Topics addressed include data processing for genome projects, programming software to compare DNA sequences, and the characterization of patterns in DNA sequences.

The archiving of qualitative data seems likely to become much more common in the future. It promises to make an important contribution to the development of sociological research. This contribution relates to at least two main areas. It should facilitate assessment of the validity of particular studies; and it ought to increase the scope for secondary analysis. At the same time, the archiving of qualitative data and its use are not without problems. This paper examines both the possibilities it opens up and the limits to the contribution it can make. Key words: qualitative research methodology, archiving qualitative data, assessment of research findings, secondary analysis of qualitative data.

A study of executive preferences for information processing methods shows that the behavior affecting their options may not be attributed to a single theory except by an implied theoretical explanation. Volatile environments, the adaptability of systems and levels of planning all contribute to the differences in planning scenarios. These differences affect executives' search for information and the appropriate information processing method. Eight information processing tools are evaluated in terms of executive preferences in a situational context.