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- Andersson, Karl, 1972-
(författare)
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Characterization of Biomolecular Interactions Using a Multivariate Approach
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents a novel bioinformatic methodology denoted the bio-chemometric approach. The methodology is designed for generation of detailed descriptions and predictions of biomolecular interactions. It is based on multivariate analysis of the sensitivity of a biomolecular interaction to multiple minor changes in the experimental conditions. In this work, either the chemical environment where the interaction takes place, or the molecular structure of one of the interacting molecules, was varied. The sensitivity of the interaction to the performed variations was presented as a vector called the sensitivity fingerprint. The bio-chemometric approach was tested on several biomolecular interactions. Useful descriptions of the interactions were obtained by measuring binding kinetics for each interaction in 12-20 different buffers and correlating buffer composition to binding kinetics. The obtained chemical sensitivity fingerprints were reproducible, significantly different and showed a weak correlation to binding site properties for the tested interactions. The results indicate that the fingerprints contained useful information about the binding site. The predictive ability of the bio-chemometric approach was tested on two different biomolecular interactions where one of the binding partners was slightly modified into multiple analogues by amino acid exchanges. In one example, interactions of 18 peptide analogues with an antibody gave data that could be used for accurate prediction of the dissociation rates of novel analogues. Reliable predictions of binding kinetics and affinity were also obtained for single domain camel antibody analogues binding to a protein antigen. By using the three-dimensional structure of camel antibodies and data obtained using the bio-chemometric approach, even the importance of non-exchanged amino acids for the binding could be estimated. The bio-chemometric approach can potentially improve the development of peptides and proteins for therapeutic and diagnostic use. It is suggested to be valid for general use in biochemistry.
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| 4. |
- Antonson, Hans, et al.
(författare)
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Bedömning av skada på bevarandeintressen : ett kunskapsunderlag inför en metodutveckling
- 2002
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Bedömning av skada på bevarandeintressen är ofta en svag punkt i miljökonsekvensbeskrivningar (MKB). Generell metodutveckling i detta avseende behövs som stöd för utförare av analyser och beskrivningar för vägprojekt. Projektet Bedömning av skada på bevarandeintressen har haft som uppgift att utveckla en metod som kan bedöma skada på skyddade områden för natur, kultur eller friluftsliv. De studerade områdestyperna är riksintresseområden och Natura-2000-områden.Studien bygger på en större genomgång av bl.a. svensk, europeisk och överstatlig handboks- eller utbildningslitteratur, utredningsmaterial från infrastrukturprojekt samt gällande riktlinjer och lagar. Ur denna genomgång belystes bl.a. följande aspekter: de miljöaspekter vilka utpekas kan skadas, hur skada bedöms, hur påverkan, effekt och konsekvens beskrivs, vilka värderingsgrunder som används och bevarandevärdenas rättsliga grunder. Aspekterna ingick som byggstenar i en metodkonstruktion.
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- Antonson, Hans, et al.
(författare)
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Bedömning av skada på bevarandeintressen : en metodutveckling, huvudrapport
- 2002
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Assessment of damage to heritage assets is often a weak element inenvironmental impact assessments (EIA). General method development is neededin this respect as support for the authors of analyses and descriptions forroad projects. The task of the project Assessment of damage to heritageassets was to develop a method which can assess damage to protected areas fornature, culture or outdoor activities. The types of areas which have beenstudied are areas of national interest and Natura 2000 areas. The method hasbeen developed with reference to a major review of e.g. Swedish, European andsupranational handbook and educational literature, investigation materialfrom infrastructure projects, and current guidelines and laws. The method isdesigned as a checklist which deals with a number of planning stages, i.e. anumber of questions each of which must be answered before proceeding to theend of the checklist where an assessment - no damage, damage or pronounceddamage - has to be made. At the same time, those completing the checklistmust also answer a number of relevant questions in order to motivate theirstandpoint regarding the assessment of damage, both to themselves and toothers. The method has been tested on a newly produced EIA and has beenjudged by external reviewers to work well.
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| 6. |
- Antonson, Hans, et al.
(författare)
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Identifiering av samband i landskapet : ett pilotprojekt för tillämpning inom transportinfrastruktur. EKLIPS-rapport, kulturmiljö och kvartärgeologi
- 2004
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Eklips är ett samarbetsprojekt med många inblandade parter. VTI:s del harvarit att undersöka vissa samband i landskapet utifrån ordinära fält ochkartstudier. Därefter har forskare vid Metria Miljöanalys försökt identifieradessa samband automatiskt. De studerade sambanden är kända sedan länge inomkulturgeografisk och agrarhistorisk forskning. Det är samband mellan olikaföreteelser i landskap, exempelvis mellan olika bebyggelsekategorier såsommellan herrgård respektive bondgård och dess underlydande torp. Därefter harsimulering och analys av hur vägar bryter sambanden genomförts. Att försökavisualisera sambanden har också varit viktigt i arbetet samt att försökaförstå hur sambanden uppfattas när man lyfter blicken från kartan till detfaktiska landskapet. Vi har kommit fram till slutsatsen att sambanden måstevara konkreta för att kunna uppfattas, dvs. om man skall kunna förstå måsteman också kunna se. Det räcker således inte med att sambanden går attgrafiskt visualisera på en karta. De måste kunna upplevas i landskapet föratt kunna pekas ut som exempelvis bevarandevärda eller hänsynsvärda.
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| 7. |
- Antonson, Hans, 1963-, et al.
(författare)
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Transportrelaterad miljökvalitet : rapport från workshop den 10-11 september 2001
- 2001
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Rapport (populärvet., debatt m.m.)abstract
- Under 10–11 september 2001 möttes 31 representanter från departement, myndigheter, forskningsfinansiärer och forskarsamhället på Scandic hotell Hasselbacken i Stockholm för att lyssna till föredragningar om och diskutera kring begreppet transportrelaterad miljökvalitet.Initiativet till workshopen togs av VTI (Statens väg- och transportforskningsinstitut) genom en delansökan i en bred ansökan kallad Tema miljökvalitet ställd till Vägverket, Banverket och KFB.Workshopens syfte var att diskutera begreppet miljökvalitet i relation till transportsektorn och att rekognosera intresset för bildandet av ett nätverk för transportrelaterad miljökvalitet. För att underlätta urvalsarbetet och göra workshopen hanterbar inbjöds ett antal gäster från departement, myndigheter, forskningsfinansiärer och forskarsamhället som alla hade relevanta kunskaper och erfarenheter inom området.
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| 8. |
- Asraf, Daniel, et al.
(författare)
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An analytical series expansion solution to the problem of noncoherent detection
- 2004
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Ingår i: IEEE Transactions on Information Theory. - 0018-9448 .- 1557-9654. ; 50:12, s. 3369-3375
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Tidskriftsartikel (refereegranskat)abstract
- The well-known noncoherent detection problem concerns optimal detection of an amplitude-modulated sinusoid, with an unknown phase angle, corrupted by additive Gaussian noise. The classical solution to this problem is the noncoherent detector which is known to be optimal if the envelope belongs to a specific set of functions or satisfies the narrow-band approximation i.e., that the bandwidth of the envelope is narrow in comparison with the (carrier) frequency of the sinusoid. In this work, an analytical series expansion solution to the likelihood ratio for the noncoherent detection problem is derived. This solution offers a generalization of the noncoherent detector in which the conditions imposed on the envelope stated above have been relaxed. Analytical expressions for the joint probability density functions (pdfs) of the in-phase and quadrature components, jointly expressed in polar coordinates, are also derived under the signal-plus-noise and the noise-only hypotheses, respectively. Numerical simulations of the detector performance are presented in the form of receiver operating characteristics (ROC) and minimum probability of error curves. The results from a comparison of the general analytical solution with the classical noncoherent detector show significant differences between the two detectors when the narrow-band approximation does not hold.
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| 9. |
- Asraf, Daniel, et al.
(författare)
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Optimal Detection of Crack Echo Families in Elastic Solids
- 2003
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Ingår i: The Journal of the Acoustical Society of America. ; 113:5, s. 2732-2741
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Tidskriftsartikel (refereegranskat)abstract
- Optimal detection of a striplike crack residing in an isotropic elastic solid with coarse microstructure by means of ultrasonic nondestructive evaluation (NDE) is considered. A physics-based approach to derive an optimal detector, which achieves the theoretical limitations constrained by the underlying physics, is presented. State-of-the-art physical models of crack echoes and of stochastic backscattering from the material structure in elastic solids are introduced and unified with the theory of optimal detection to yield a practically useful nonlinear filter bank implementation of the optimal detector. Monte Carlo simulations of the detection performance for the special case of a striplike crack with uncertain angular orientation are presented in the form of receiver operating characteristics (ROCs). These new results represent the physical limitations for detecting a crack under the stated conditions and serve as performance bounds to which other detectors should be compared. A physics-based generalized likelihood ratio (GLR) detector, which relies on the same nonlinear filter bank as the optimal detector, is also presented for the special case of a striplike crack. A comparison between the optimal and the GLR detectors shows that the GLR detector only slightly reduces the performance.
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| 10. |
- Asraf, Daniel
(författare)
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Optimal Detectors for Transient Signal Families and Nonlinear Sensors : Derivations and Applications
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is concerned with detection of transient signal families and detectors in nonlinear static sensor systems. The detection problems are treated within the framework of likelihood ratio based binary hypothesis testing.An analytical solution to the noncoherent detection problem is derived, which in contrast to the classical noncoherent detector, is optimal for wideband signals. An optimal detector for multiple transient signals with unknown arrival times is also derived and shown to yield higher detection performance compared to the classical approach based on the generalized likelihood ratio test.An application that is treated in some detail is that of ultrasonic nondestructive testing, particularly pulse-echo detection of defects in elastic solids. The defect detection problem is cast as a composite hypothesis test and a methodology, based on physical models, for designing statistically optimal detectors for cracks in elastic solids is presented. Detectors for defects with low computational complexity are also formulated based on a simple phenomenological model of the defect echoes. The performance of these detectors are compared with the physical model-based optimal detector and is shown to yield moderate performance degradation.Various aspects of optimal detection in static nonlinear sensor systems are also treated, in particular the stochastic resonance (SR) phenomenon which, in this context, implies noise enhanced detectability. Traditionally, SR has been quantified by means of the signal-to-noise ratio (SNR) and interpreted as an increase of a system's information processing capability. Instead of the SNR, rigorous information theoretic distance measures, which truly can support the claim of noise enhanced information processing capability, are proposed as quantifiers for SR. Optimal detectors are formulated for two static nonlinear sensor systems and shown to exhibit noise enhanced detectability.
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