| 1. |
- Al-Askary, Omar, 1965-
(författare)
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Coding and Iterative Decoding of Concentrated Multi-level Codes for the Rayleigh Fading Channel
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis we present the concept of concatenated multilevel codes. These codes are a combination of generalized concatenated codes with multilevel coding. The structure of these codes is simple and relies on the concatenation of two or more codes of shorter length. These codes can be designed to have large diversity which makes them attractive for use in fading channels. We also present an iterative decoding algorithm taylored to fit the properties of the proposed codes. The iterative decoding algorithm we present has a complexity comparable to the complexity of GMD decoding of the same codes. However, The gain obtained by using the iterative decoder as compared to GMD decdoing of these codes is quite high for Rayleigh fading channels at bit error rates of interest. Some bounds on the performance of these codes are given in this thesis. Some of the bounds are information theoretic bounds which can be used regardless of the code under study. Other bounds are on the error probability of concatenated multilevel codes. Finally we give examples on the implementation of these codes in adaptive coding of OFDM channels and MIMO channels.
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| 2. |
- All, Rainar, et al.
(författare)
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Olyckor, riskanalyser och säkerhetsarbete : Några olika perspektiv inom Räddningsverket
- 2006
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Annan publikation (populärvet., debatt m.m.)abstract
- SammanfattningSyftet med denna kartläggning har varit att ge en nulägesbild över hur riskanalyser, riskbedömningar och riskvärderingar sker i Räddningsverkets arbete med skydd mot olyckor. Ett syfte har också varit att beskriva de olika strategier för säkerhetsarbete som tillämpas i myndigheten.Kartläggningen har utförts genom gruppintervjuer under perioden oktober 2004 mars 2005 och har följts upp med hjälp av två seminarier i november 2005. Analysgruppen har bestått av medarbetare vid Räddningsverkets sekretariat för forskning och analys.Resultaten visar bland annat att:- verkets arbete utgår från en kompott av olyckor, skador och händelser, var och en med sin egen logik baserad på tradition, lagstiftning och politisk inriktning- arbetet bedrivs utifrån en mångfald av strategier som i många fall inte är produkten av genomtänkta analyser och medvetna val- verkets olika roller behöver närmare analyseras och kopplas till tydligarestrategier och metoder för arbetet med skydd mot olyckor- säkerhetsarbete och riskhantering är inte synonyma begrepp i myndigheten- det saknas myndighetsgemensamma begreppsdefinitioner inom det kartlagdaområdet- det råder en brist i myndigheten på djupare diskussioner och reflektioner kring värdegrunder och principer för riskvärdering.Rapporten behandlar många olika frågor som på olika sätt är relevanta för Räddningsverkets arbete på kort och lång sikt. I rapporten ges ett tiotal förslag till fortsatt arbete. Några förslag är att:- utarbeta en begreppspolicy för myndigheten- utarbeta information till privatpersoner som lagenliga skyldigheter inom det olycksförebyggande området- satsa på kompetensutveckling internt- starta ett utvecklingsarbete inom riskvärdering- utveckla analysförmåga för framtidens olycksrisk- starta en idéverkstad för framtida säkerhetsarbeteKartläggningen ska ligga till grund för fortsatt utvecklingsarbete inom Räddningsverket. Delar av materialet kan också komma att utgöra underlag förutveckling av läromedel för verkets utbildningsverksamhet. Rapporten utgör också en möjlig källa för fortsatt forskning och analys inom området
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| 3. |
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| 4. |
- Arvidsson, Sara, et al.
(författare)
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Intelligenta försäkringar för person- och lastbilar
- 2006
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Rapport (populärvet., debatt m.m.)abstract
- Within the European Union there are annually about 1 300 000 accidents with physical injuries. Estimates indicate that accident costs add up to €160 billion, corresponding to 2 percent of the Union's GDP. On Sweden's roads alone 400-500 people are killed annualy and thousands are injured. Traffic accidents are, like in most other countries, one of the country's national health problems. Substantial resources are allocated to reduce the number of accidents and their consequences, once an accident occurs. The insurance industry is one part in this. The focus of this report is how insurance companies design their insurance premiums and the possibility to change this design in order to curb accident risks. Our starting point is that modern techniques makes it feasible to link the way in which the premium is calculated to actual behaviour. The fast development of in-vehicle "black box" technology provides prerequisits for observing driver behaviour and in particular speed relative to speed limits. By making speeders pay more than drivers that adhere to speed limits, the insurance system may affect average speed on the road network and consequently also the number and consequences of accidents. The report is made up of three parts. The first presents a review of international experiences of "Pay-as-You-Drive" and "Pay-as-You-Speed" applications. The second reviews technical aspects and the options available when selecting an appropriate solution. A third paper presents a blueprint for the way in which an insurance premium based on "Pay-as-You-Speed" could be designed in order to capture important incentive aspects of the system. It is suggested that the insurance industry should go ahead with the development of these techniques. It is, however, also acknowledged that the incentives of the industry may be insuffient to carry the implementation costs. Since society at large carries much more of the accident costs than the industry itself, this provides prima facie motive for government intervention in order to avoid a market failure. It is argued that the costs for establishing an open technical platform in vehicles and to organise the collection of data may be small relative to the potential benefits of the system.
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| 5. |
- Carlsson, Gunnar E, 1930, et al.
(författare)
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Trends in prosthodontics
- 2006
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Ingår i: Med Princ Pract. ; 15, s. 167-179
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Tidskriftsartikel (refereegranskat)abstract
- Prosthodontics is concerned with the impact of loss of teeth and the resulting damage to teeth or tissue, oral function in its broadest sense. It deals with this largely through prosthetic replacement. The discipline occupies a major portion of dental school curriculum, and dental practitioners usually devote much of their practice to prosthodontic services. With the rapid improvement in oral health and the reduction of edentulism in many countries, increasing numbers of people are retaining more teeth later in life. Consequently, the main focus in prosthodontics has shifted from removable dentures to fixed prostheses, while implant-supported restorations have attracted intense interest in the dental community. Another factor increasingly influencing prosthodontic practice is patients’ awareness of newer technologies in aesthetic dentistry. Because maintenance and repair as well as prosthodontic interventions, are by nature costly, the global development in the field manifests fundamental inequities in the levels of services that patients can access. Diminishing resources for healthcare in general challenges educators and practitioners of prosthodontics alike. This review is an attempt to describe the recent developments in prosthodontics, its therapeutic areas and impact on the theory and practice of the discipline.
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| 6. |
- Gutierrez Arenas, Omar, 1975-, et al.
(författare)
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Detection of competitive enzyme inhibition with end point progress curve data
- 2006
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Ingår i: Analytical Biochemistry. - : Elsevier BV. - 0003-2697 .- 1096-0309. ; 358:1, s. 11-19
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Tidskriftsartikel (refereegranskat)abstract
- A model for a dimensionless factor, the inhibition detection limit (IDL), which describes the limit of detection of competitive inhibition for end point assays as a function of the proportion of substrate converted into product, has been developed. For a given end point enzymatic assay, the IDL function has a maximum that is dependent on the error structure parameters (four parameters) of the assay, the value of [S]o/K(ms), and the extent of product inhibition (K(ms)/K(mp)). Accordingly, the substrate conversion level that maximized the ability to detect samples with high Ki/[I] ratios was predicted for each member of a population of simulated assays. Furthermore, we identified a consensus substrate conversion level where the probability of a near-optimal robustness and detection limit for all the members of the assay population is maximal. Unlike the optimal substrate conversion level for individual assays, this consensus substrate conversion level was dependent only on [S]o/K(m), K(ms)/K(mp), and whether the signal increases or decreases during the course of the reaction. Consensus substrate conversion levels were beyond the initial velocity range for almost all the analyzed assay populations. It was shown that the IDL factor was a more informative indicator of assay quality than the popular Z' factor.
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| 7. |
- Gutierrez Arenas, Omar, et al.
(författare)
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Sensitivity analysis and error structure of progress curves
- 2006
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Ingår i: Analytical Biochemistry. - : Elsevier BV. - 0003-2697 .- 1096-0309. ; 358:1, s. 1-10
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Tidskriftsartikel (refereegranskat)abstract
- Both the sensitivity of the monitored signal in progress curves to variations in enzyme concentration and the standard deviation of this signal were analyzed as a function of the proportion of transformed substrate. Three enzymes catalyzing essentially irreversible reactions were used as model systems: HIV-1 protease, glutathione reductase, and glutathione transferase. For all enzymes analyzed, the sensitivity was maximal when 60-80% of the substrate had been transformed. The standard deviation of reaction progress curve data replicates was also maximal at these substrate conversion levels, a result that was attributed to the influence of the sensitivity to random dispersion of the enzyme concentration. On this basis, we developed a model for the standard deviation of reaction progress curves that gave a good description of the experimental data and efficiently reduced the heteroscedasticity of residuals in a weighted fit of progress curves. This standard deviation model can be used for obtaining more efficient parameter estimates, to simulate noise in Monte Carlo procedures, and to delineate detection limits of enzyme inhibition. The transient increases in the sensitivity and in the standard deviation in progress curves are proposed to be features common to most enzymatic assays.
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| 8. |
- Gutierrez Arenas, Omar
(författare)
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Sensitivity, Noise and Detection of Enzyme Inhibition in Progress Curves
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Starting with the development of an enzymatic assay, where an enzyme in solution hydrolysed a solid-phase bound peptide, a model for the kinetics of enzyme action was introduced. This model allowed the estimation of kinetic parameters and enzyme activity for a system that has the peculiarity of not being saturable with the substrate, but with the enzyme. In a derivation of the model, it was found that the sensitivity of the signal to variations in the enzyme concentration had a transient increase along the reaction progress with a maximum at high substrate conversion levels.The same behaviour was derived for the sensitivity in classical homogeneous enzymatic assays and experimental evidence of this was obtained. The impact of the transient increase of the sensitivity on the error structure, and on the ability of homogeneous end-point enzymatic assays to detect competitive inhibition, came into focus. First, a non-monotonous shape in the standard deviation of progress curve data was found and it was attributed to the random dispersion in the enzyme concentration operating through the transient increase in the sensitivity. Second, a model for the detection limit of the quantity Ki/[I] (the IDL-factor) as a function of the substrate conversion level was developed for homogeneous end-point enzymatic assays.It was found that the substrate conversion level where the IDL-factor reached an optimum was beyond the initial velocity range. Moreover, at this optimal point not only the ability to detect inhibitors but also the robustness of the assays was maximized. These results may prove to be relevant in drug discovery for optimising end point homogeneous enzymatic assays that are used to find inhibitors against a target enzyme in compound libraries, which are usually big (>10000) and crowded with irrelevant compounds.
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| 9. |
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| 10. |
- Stewart, Tracy L, et al.
(författare)
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Haplotypes defined by promoter and intron 1 polymorphisms of the COLIA1 gene regulate bone mineral density in women
- 2006
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Ingår i: Journal of Clinical Endocrinology and Metabolism. - : The Endocrine Society. - 1945-7197 .- 0021-972X. ; 91:9, s. 3575-3583
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Tidskriftsartikel (refereegranskat)abstract
- CONTEXT: The COLIA1 gene is a strong candidate for susceptibility to osteoporosis. The causal genetic variants are currently unclear, but the most likely are functional polymorphisms in the promoter and intron 1 of COLIA1. OBJECTIVE: The objective of the study was to determine whether promoter and intron 1 polymorphisms of COLIA1 or haplotypes defined by these polymorphisms regulate bone mineral density (BMD) in women. DESIGN: This was a population-based association study involving 3270 women from the United Kingdom who took part in a regional osteoporosis screening program. MAIN OUTCOME MEASURES: BMD at the lumbar spine (LS-BMD) and femoral neck (FN-BMD) was measured on two occasions approximately 6 yr apart, in relation to polymorphisms and haplotypes defined by polymorphisms within the COLIA1 intron 1 (+1245G/T; rs1800012) and promoter (-1997G/T; rs1107946; -1663IndelT; rs2412298). RESULTS: The polymorphisms were in strong linkage disequilibrium, and three haplotypes accounted for more than 95% of alleles at the COLIA1 locus. The individual polymorphisms were associated with BMD, but the most consistent associations were with haplotypes defined by all three polymorphisms. Homozygote carriers of haplotype 2 (-1997G/-1663delT/+1245T) had reduced BMD at baseline (P = 0.007 for LS-BMD; P = 0.008 for FN-BMD), whereas homozygotes for haplotype 3 (-1997T/-1663insT/+1245G) had increased BMD (P = 0.007 for LS-BMD). Similar associations were observed at follow-up for haplotype 3, but the association with haplotype 2 was weaker due to increased uptake of hormone replacement therapy in homozygotes for this haplotype. CONCLUSIONS: Two haplotypes defined by polymorphisms in the 5' flank of the COLIA1 regulate BMD in a bidirectional manner in women.
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