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- Lindqvist, Anders, et al.
(author)
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Long-term effects of Ca(2+) on structure and contractility of vascular smooth muscle
- 1999
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In: American Journal of Physiology: Cell Physiology. - 1522-1563. ; 277:1, s. 64-73
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Journal article (peer-reviewed)abstract
- Culture of dispersed smooth muscle cells is known to cause rapid modulation from the contractile to the synthetic cellular phenotype. However, organ culture of smooth muscle tissue, with maintained extracellular matrix and cell-cell contacts, may facilitate maintenance of the contractile phenotype. To test the influence of culture conditions, structural, functional, and biochemical properties of rat tail arterial rings were investigated after culture. Rings were cultured for 4 days in the absence and presence of 10% FCS and then mounted for physiological experiments. Intracellular Ca(2+) concentration ([Ca(2+)](i)) after stimulation with norepinephrine was similar in rings cultured with and without FCS, whereas force development after FCS was decreased by >50%. The difference persisted after permeabilization with beta-escin. These effects were associated with the presence of vasoconstrictors in FCS and were dissociated from its growth-stimulatory action. FCS treatment increased lactate production but did not affect ATP, ADP, or AMP contents. The contents of actin and myosin were decreased by culture but similar for all culture conditions. There was no effect of FCS on calponin contents or myosin SM1/SM2 isoform composition, nor was there any appearance of nonmuscle myosin. FCS-stimulated rings showed evidence of cell degeneration not found after culture without FCS or with FCS + verapamil (1 microM) to lower [Ca(2+)](i). The decreased force-generating ability after culture with FCS is thus associated with increased [Ca(2+)](i) during culture and not primarily caused by growth-associated modulation of cells from the contractile to the synthetic phenotype.
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- Lindqvist, Ulf, 1970, et al.
(author)
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An analysis of a secure system based on trusted components
- 1996
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In: IEEE Proceedings of the Eleventh Annual Conference on Computer Assurance, COMPASS '96. ; , s. 213-223
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Conference paper (peer-reviewed)abstract
- The paper presents a practical security analysis of a beta implementation of a commercial system based on existing trusted hardware components, such as advanced cryptographic building blocks. The system was designed to securely store and handle both sensitive and insensitive data records on individuals in such a way that it would be impossible for unauthorized parties to link sensitive records to the corresponding individuals. The analysis was performed by means of document reviews, interviews and some practical tests with the intention of finding and listing potential vulnerabilities for the knowledge of the design team. The vulnerabilities revealed are classified with respect to their cause, and possible remedies are discussed. The classification shows that the most important problem was that some system components were incorrectly handled as trusted. Finally, we observed that the problems were to a surprisingly high degree non technical, reflecting organisational and management issues and human insufficiencies.
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- Lindqvist, Ulf, 1970, et al.
(author)
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How to systematically classify computer security intrusions
- 1997
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In: IEEE Symposium on Security and Privacy, 1997. Proceedings.. - 1081-6011. - 0818678283
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Conference paper (peer-reviewed)abstract
- This paper presents a classification of intrusions with respect to the technique as well the result. The taxonomy is intended to be a step on the road to an established taxonomy of intrusions for use in incident reporting, statistics, warning bulletins, intrusion detection systems etc. Unlike previous schemes, it takes the viewpoint of the system owner and should therefore be suitable to a wider community than that of system developers and vendors only. It is based on data from a realistic intrusion experiment, a fact that supports the practical applicability of the scheme. The paper also discusses general aspects of classification, and introduces a concept called dimension. After having made a broad survey of previous work in the field, we decided to base our classification of intrusion techniques on a scheme proposed by Neumann and Parker (1989) and to further refine relevant parts of their scheme. Our classification of intrusion results is derived from the traditional three aspects of computer security: confidentiality, availability and integrity
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- Lindqvist, Ulf, 1970
(author)
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On the Fundamentals of Analysis and Detection of Computer Misuse
- 1999
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Doctoral thesis (other academic/artistic)abstract
- Most computerized information systems we use in our everyday lives provide very little protection against hostile manipulation. At the same time, there is a rapidly increasing dependence on services provided by these computer systems and networks, and security is thus not only an interesting and challenging research discipline but has indeed developed into a critical issue for society. This thesis presents research focused on the fundamental technical issues of computer misuse, aimed at manual analysis and automatic detection. The objective is to analyze and understand the technical nature of security threats and, on the basis of this, develop efficient generic methods that can improve the security of existing and future systems. The work is performed from the perspective of system and information owners, a different approach compared to the many previous studies that focus on system developers only. The analysis is based mainly on empirical data from student experiments but also uses data from a security analysis, data recorded from a network server and data produced for an intrusion detection evaluation project. Throughout this work, systematic categorization of data has been used as the main method for data analysis. The results of this work include new findings about the behavior of so-called insider attackers, a dangerous but sometimes neglected security threat. For systems that include commercial off-the-shelf components, underlying causes of system vulnerabilities are identified and discussed, a systematic procedure for vulnerability remediation is developed and a risk management strategy is proposed. Furthermore, the aspects of computer misuse that are fundamental for automatic detection are identified and analyzed in detail. The efficiency and usability of a generic expert system tool for automatic misuse detection is verified empirically. A general database format for documenting attack types and for automatically updating detection tools is outlined.
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