| 1. |
- Lindgren, Petter, et al.
(författare)
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A likelihood ratio-based approach for improved source attribution in microbiological forensic investigations
- 2019
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Ingår i: Forensic Science International. - : Elsevier. - 0379-0738 .- 1872-6283. ; 302
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Tidskriftsartikel (refereegranskat)abstract
- A common objective in microbial forensic investigations is to identify the origin of a recovered pathogenic bacterium by DNA sequencing. However, there is currently no consensus about how degrees of belief in such origin hypotheses should be quantified, interpreted, and communicated to wider audiences. To fill this gap, we have developed a concept based on calculating probabilistic evidential values for microbial forensic hypotheses. The likelihood-ratio method underpinning this concept is widely used in other forensic fields, such as human DNA matching, where results are readily interpretable and have been successfully communicated in juridical hearings. The concept was applied to two case scenarios of interest in microbial forensics: (1) identifying source cultures among series of very similar cultures generated by parallel serial passage of the Tier 1 pathogen Francisella tularensis, and (2) finding the production facilities of strains isolated in a real disease outbreak caused by the human pathogen Listeria monocytogenes. Evidence values for the studied hypotheses were computed based on signatures derived from whole genome sequencing data, including deep-sequenced low-frequency variants and structural variants such as duplications and deletions acquired during serial passages. In the F. tularensis case study, we were able to correctly assign fictive evidence samples to the correct culture batches of origin on the basis of structural variant data. By setting up relevant hypotheses and using data on cultivated batch sources to define the reference populations under each hypothesis, evidential values could be calculated. The results show that extremely similar strains can be separated on the basis of amplified mutational patterns identified by high-throughput sequencing. In the L. monocytogenes scenario, analyses of whole genome sequence data conclusively assigned the clinical samples to specific sources of origin, and conclusions were formulated to facilitate communication of the findings. Taken together, these findings demonstrate the potential of using bacterial whole genome sequencing data, including data on both low frequency SNP signatures and structural variants, to calculate evidence values that facilitate interpretation and communication of the results. The concept could be applied in diverse scenarios, including both epidemiological and forensic source tracking of bacterial infectious disease outbreaks.
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| 2. |
- Ahlinder, Jon, et al.
(författare)
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Chemometrics comes to court: evidence evaluation of chem–bio threat agent attacks
- 2015
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Ingår i: Journal of Chemometrics. - : John Wiley & Sons. - 0886-9383 .- 1099-128X. ; 29:5, s. 267-276
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Tidskriftsartikel (refereegranskat)abstract
- Forensic statistics is a well-established scientific field whose purpose is to statistically analyze evidence in order to support legal decisions. It traditionally relies on methods that assume small numbers of independent variables and multiple samples. Unfortunately, such methods are less applicable when dealing with highly correlated multivariate data sets such as those generated by emerging high throughput analytical technologies. Chemometrics is a field that has a wealth of methods for the analysis of such complex data sets, so it would be desirable to combine the two fields in order to identify best practices for forensic statistics in the future. This paper provides a brief introduction to forensic statistics and describes how chemometrics could be integrated with its established methods to improve the evaluation of evidence in court.The paper describes how statistics and chemometrics can be integrated, by analyzing a previous know forensic data set composed of bacterial communities from fingerprints. The presented strategy can be applied in cases where chemical and biological threat agents have been illegally disposed.
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| 3. |
- Wittgren, Hans B, et al.
(författare)
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An actor game on implementation of environmental quality standards for nitrogen in a Swedish agricultural catchment
- 2005
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Ingår i: Ambio. - : Royal Swedish Academy of Sciences. - 0044-7447 .- 1654-7209. ; 34:3, s. 237-247
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Tidskriftsartikel (refereegranskat)abstract
- Despite political efforts, diffuse pollution from agriculture continues to be the single largest source of nitrogen (N) emissions into the aquatic environment in many countries and regions. This fact, and the recent enactment of a new Swedish environmental code, led to the design of a study targeted at the evaluation of new N pollution abatement strategies. An actor game was chosen as the key component of the study, with a focus on four major goals: to test the implementability of legally binding environmental quality standards for nitrate concentration in groundwater and N transport to the sea, to find sets of agriculturally feasible and cost-effective measures to decrease N loads, to investigate the possibilities for collective action through negotiated and institutionalized actor cooperation, and to investigate the role of mathematical modeling in environmental N management. Characteristics from the agriculturally dominated catchment of Genevadsan (224 km(2)) on the southwest coast of Sweden served as the playing field for the actor game. The most noteworthy result from the study was that it appeared to be possible to meet ambitious environmental N standards with less economically drastic measures than anticipated by most of the participants. The actor game was shown to be a good method for learning about the new Swedish environmental code and its application and for gaining deeper insight into the issues of N management. In addition, the actor game functioned as an arena for gaining a more thorough understanding of the views of different stakeholders.
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| 4. |
- Ansell, Ricky, et al.
(författare)
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Interpretation of DNA Evidence: Implications of Thresholds Used in the Forensic Laboratory
- 2014
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Evaluation of forensic evidence is a process lined with decisions and balancing, not infrequently with a substantial deal of subjectivity. Already at the crime scene a lot of decisions have to be made about search strategies, the amount of evidence and traces recovered, later prioritised and sent further to the forensic laboratory etc. Within the laboratory there must be several criteria (often in terms of numbers) on how much and what parts of the material should be analysed. In addition there is often a restricted timeframe for delivery of a statement to the commissioner, which in reality might influence on the work done. The path of DNA evidence from the recovery of a trace at the crime scene to the interpretation and evaluation made in court involves several decisions based on cut-offs of different kinds. These include quality assurance thresholds like limits of detection and quantitation, but also less strictly defined thresholds like upper limits on prevalence of alleles not observed in DNA databases. In a verbal scale of conclusions there are lower limits on likelihood ratios for DNA evidence above which the evidence can be said to strongly support, very strongly support, etc. a proposition about the source of the evidence. Such thresholds may be arbitrarily chosen or based on logical reasoning with probabilities. However, likelihood ratios for DNA evidence depend strongly on the population of potential donors, and this may not be understood among the end-users of such a verbal scale. Even apparently strong DNA evidence against a suspect may be reported on each side of a threshold in the scale depending on whether a close relative is part of the donor population or not. In this presentation we review the use of thresholds and cut-offs in DNA analysis and interpretation and investigate the sensitivity of the final evaluation to how such rules are defined. In particular we show what are the effects of cut-offs when multiple propositions about alternative sources of a trace cannot be avoided, e.g. when there are close relatives to the suspect with high propensities to have left the trace. Moreover, we discuss the possibility of including costs (in terms of time or money) for a decision-theoretic approach in which expected values of information could be analysed.
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| 5. |
- Bovens, Michael, et al.
(författare)
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Chemometrics in forensic chemistry — Part I: Implications to the forensic workflow
- 2019
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Ingår i: Forensic Science International. - : Elsevier BV. - 0379-0738 .- 1872-6283. ; 301, s. 82-90
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Tidskriftsartikel (refereegranskat)abstract
- The forensic literature shows a clear trend towards increasing use of chemometrics (i.e. multivariate analysis and other statistical methods). This can be seen in different disciplines such as drug profiling, arson debris analysis, spectral imaging, glass analysis, age determination, and more. In particular, current chemometric applications cover low-dimensional (e.g. drug impurity profiles) and high-dimensional data (e.g. Infrared and Raman spectra) and are therefore useful in many forensic disciplines. There is a dominant and increasing need in forensic chemistry for reliable and structured processing and interpretation of analytical data. This is especially true when classification (grouping) or profiling (batch comparison) is of interest.Chemometrics can provide additional information in complex crime cases and enhance productivity by improving the processes of data handling and interpretation in various applications. However, the use of chemometrics in everyday work tasks is often considered demanding by forensic scientists and, consequently, they are only reluctantly used. This article and following planned contributions are dedicated to those forensic chemists, interested in applying chemometrics but for any reasons are limited in the proper application of statistical tools — usually made for professionals — or the direct support of statisticians. Without claiming to be comprehensive, the literature reviewed revealed a sufficient overview towards the preferably used data handling and chemometric methods used to answer the forensic question. With this basis, a software tool will be designed (part of the EU project STEFA-G02) and handed out to forensic chemist with all necessary elements of data handling and evaluation.Because practical casework is less and less accompanied from the beginning to the end out of the same hand, more and more interfaces are built in through specialization of individuals. This article presents key influencing elements in the forensic workflow related to the most meaningful chemometric application and evaluation.
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| 6. |
- Nehler, Therese, 1976-, et al.
(författare)
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Sammanställning av kunskapsläget kring gällande regelverk för bio-CCS i Sverige
- 2021
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Avskiljning och geologisk lagring av biogen koldioxid (bio-CCS) utgör en potentiellt viktig kompletterande åtgärd i att nå Sveriges mål om noll nettoutsläpp av växthusgaser år 2045 och därefter negativa utsläpp. Potentialen för att skapa negativa utsläpp via bio-CCS i Sverige bedöms som god, men i gällande lagar och regelverk finns fortfarande utmaningar att ta hänsyn till och lösa för att verksamhetsutövare ska kunna tillämpa tekniken. Denna rapport belyser och ger ett nuläge av de områden i regelverket som behöver behandlas för att möjliggöra investeringar och drift av bio-CCS anläggningar för verksamhetsutövare inom massa- och pappersindustrin och el- och fjärrvärmeproduktion inklusive avfallsförbränning. Rapporten sammanfattar även gällande regelverk på internationell nivå, EU-nivå och nationell nivå. Områden som kräver behandling inför en framtida implementering av bio-CCS är bland annat hur negativa utsläpp ska beräknas och redovisas genom kedjan för bio-CCS, hur moratoriet kring biologisk mångfald kopplar till bio-CCS och bilaterala avtal mellan Sverige och lagringsstat.
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| 7. |
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| 8. |
- Bulut, Ozgur, et al.
(författare)
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Sexual dimorphism in frontal bone roundness quantified by a novel 3D-based and landmark-free method
- 2016
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Ingår i: Forensic Science International. - : Elsevier BV. - 0379-0738 .- 1872-6283. ; 261, s. 162.e1-162.e5
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Tidskriftsartikel (refereegranskat)abstract
- In this study we present a novel and landmark-free method for quantifying shape differences between male and female frontal bones. CT scans were recorded for 80 male and 80 female Turkish hospital patients, age 25-40. The frontal bones were first isolated from the 3D models by digital cutting along the bordering sutures, and then aligned to a CAD-based sphere. This allowed us to quantify the amount of frontal bone overlapping with the sphere (on average 43.2 +/- 6.5% for males and 33.9 +/- 6.6% for females, the difference is significant at p < 0.0001), and to identify areas of shape difference and deviation from the sphere surface in male and female bones. The larger proportion of spherical frontal bone surface in males challenges the common description of the female forehead as rounder''. Based on the overlap data, we developed discriminant functions able to correctly classify 77.5% of the frontal bone models as male/female. This demonstrates that 3D-based and landmark-free approaches to statistical shape analysis may become a viable alternative to the currently dominating landmark-based approaches for shape investigation.
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| 9. |
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| 10. |
- Bartelink, Eric J., et al.
(författare)
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A Case of Contested Cremains Analyzed Through Metric and Chemical Comparison
- 2015
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Ingår i: Journal of Forensic Sciences. - : Wiley. - 0022-1198 .- 1556-4029. ; 60:4, s. 1068-1073
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Tidskriftsartikel (refereegranskat)abstract
- Since the 1980s, cremation has become the fastest growing area of the U.S. funeral industry. At the same time, the number of litigations against funeral homes and cremation facilities has increased. Forensic anthropologists are often asked to determine whether the contents of an urn are actually cremated bone, and to address questions regarding the identity of the remains. This study uses both metric and chemical analyses for resolving a case of contested cremains. A cremains weight of 2021.8 g was predicted based on the decedent's reported stature and weight. However, the urn contents weighed 4173.5 g. The urn contents also contained material inconsistent with cremains (e.g., moist sediment, stones, ferrous metal). Analysis using XRD and SEM demonstrated that the urn contained thermally altered bone as well as inorganic material consistent with glass fiber cement. Although forensically challenging, cremains cases such as this one can be resolved using a multidisciplinary approach.
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