| 1. |
- Hedman, Johannes, et al.
(författare)
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A fast analysis system for forensic DNA reference samples
- 2008
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Ingår i: Forensic Science International: Genetics. - : Elsevier BV. - 1878-0326 .- 1872-4973. ; 2:3, s. 184-189
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Tidskriftsartikel (refereegranskat)abstract
- On January 1st, 2006, the Swedish legislation on obtaining DNA reference samples from Suspects and the recording of DNA profiles in databases was changed. As a result the number of samples analysed at the Swedish National Laboratory of Forensic Science (SKL) increased from about 4500 in 2005 to more than 25,000 in 2006. To meet this challenge, SKL launched a flew analysis system to create an unbroken chain, from sampling to incorporation of a profile in the national DNA database and subsequent automatic generation of digitally signed hit reports. The system integrates logistics, digital data transfer, new functions in LIMS (ForumDNA Version 4, Ida Infront AB) and laboratory automation. Buccal swab samples are secured on a FTA (R) card attached to an identity form, which is barcoded with a unique sample ID. After sampling, the police officer sends a digital request to SKL. The sample is automatically registered in LIMS and processed on delivery. The resulting DNA profiles are automatically classified according to quality using a custom-made expert system. Building the evaluation around mathematical rules makes it reproducible, standardised and minimises manual work and clerk errors. All samples are run in duplicate and the two profiles are compared within LIMS before incorporation in the database. In the first year of operation, the median time for completion of an analysis was 3 days, measured from delivery of the sample to incorporation of the profile in the national DNA database. In spite of the dramatic increase in the number of reference samples there was no backlog. (C) 2008 Elsevier Ireland Ltd. All rights reserved.
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| 2. |
- Hedman, J., et al.
(författare)
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Applying a customised DNA polymerase blend in forensic DNA profiling
- 2011
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Ingår i: Book of Abstracts. ; , s. 161-
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Konferensbidrag (refereegranskat)abstract
- Crime scene stains often contain extraneous compounds that may interfere with PCR-based DNA analysis,resulting in partial or negative/blank DNA profiles. Extensive DNA purification may remove PCR inhibitors, butinvolve a risk of DNA loss and introduction of contaminations. Customising the chemical content of the PCRreaction is a strategy that may increase PCR inhibitor tolerance without manipulating the sample. Previously wehave shown that crime scene stain analysis can be significantly improved by replacing the commonly used DNApolymerase AmpliTaq Gold with either individual alternative DNA polymerases or a blend of such enzymes [1,2].Here we present the validation of AmpFℓSTR SGM Plus with a modified PCR chemistry for routine casework,applying a 1:1 blend of the DNA polymerases ExTaq Hot Start and PicoMaxx High Fidelity. Allele callings areidentical to standard analysis, and stutters sizes and balance values are indistinguishable. The modified chemistryprovides increased resistance to PCR inhibitors, resulting in an elevated number of detected alleles for crimescene stains of both blood and secretion/saliva. Additionally, the detection limit is improved.[1] Hedman, J., Nordgaard, A., Rasmusson, B., Ansell, R. and Rådström, P. (2009) Improved forensic DNA analysis through the use of alternativeDNA polymerases and statistical modeling of DNA profiles. Biotechniques, 47, 951-958.[2] Hedman, J., Nordgaard, A., Dufva, C., Rasmusson, B., Ansell, R. and Rådström, P. (2010) Synergy between
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| 3. |
- Hedman, J., et al.
(författare)
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Applying a PCR inhibitor tolerant DNA polymerase blend in forensic DNA profiling
- 2011
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Ingår i: Forensic Science International: Genetics, Supplement Series. - : Elsevier. - 1875-1768. ; 3:1, s. e349-e350
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Tidskriftsartikel (refereegranskat)abstract
- Crime scene samples often contain extraneous compounds that may interfere with PCR-based DNA analysis, resulting in imbalanced, partial or blank/negative DNA profiles. Customising the chemical content of the PCR reaction is a strategy that may increase PCR inhibitor tolerance without manipulating the sample. We have validated a modified version of AmpFlSTR SGM Plus, replacing AmpliTaq Gold DNA polymerase with a customised blend of two alternative polymerases, ExTaq Hot Start and PicoMaxx High Fidelity. Allele calls are identical to standard analysis. Stutter sizes and balance values are indistinguishable. The modified chemistry provides increased resistance to PCR inhibitors, resulting in an elevated number of detected alleles for various problematic crime scene samples.
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| 4. |
- Jansson, Linda, et al.
(författare)
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Factors affecting DNA recovery from cartridge cases
- 2020
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Ingår i: Forensic Science International: Genetics. - : Elsevier BV. - 1872-4973 .- 1878-0326. ; 48
-
Tidskriftsartikel (refereegranskat)abstract
- Cartridge cases are often the sole items left behind after a shooting incident and DNA traces from these can identify persons connected to the shooting. However, the chance of retrieving usable DNA profiles from cartridge cases is limited, due to the low amounts of deposited DNA and subsequent DNA loss associated with the firing process. In the current study, we set out to increase the DNA recovery from cartridge cases and cartridges by evaluating different swab types and detergents used for trace collection. A protocol applying nylon-flocked swabs instead of cotton swabs was implemented in casework at the Swedish National Forensic Centre (NFC), increasing DNA yield. The number of samples providing a DNA concentration ≥ 0.001 ng/μL (the in-house cut-off for processing low-template samples) increased from 11.1 to 28.6 % for cartridge cases and from 16.0 to 43.3 % for cartridges. There was also a substantial increase in mixed STR profiles, too complex to use for comparisons. Thus, it was not possible to take the full advantage of the elevated DNA yield provided by nylon-flocked swabs. The number of usable STR profiles increased from 5.0 to 8.0 % for cartridge cases and remained unchanged for cartridges. Controlled studies were performed to assess the impact on the DNA recovery from different persons handling the ammunition, different material and size of the cartridge cases, and the type of firearm used. These studies reflected an ideal situation, where all cartridges were extensively handled and loaded without gloves, thus providing a higher expected DNA yield compared to most casework samples. The total peak height differed by up to a factor of ∼50 when 20 different persons handled cartridges prior to shooting. By evaluating eleven combinations of different firearms and ammunition, it was found that the casing material and type of firearm also have a substantial impact on DNA yield.
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| 5. |
- Aarts, B., et al.
(författare)
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DNActivity: International cooperation in activity level interpretation of forensic DNA evidence.
- 2015
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Ingår i: Abstract book, 7<sup>th</sup> European Academy of Forensic Science, EAFS, Prag, Tjeckien, 2015.. ; , s. 555-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Questions posed to expert witnesses by the legal community and the courts are expanding to include not just those relating to source level (i.e. ‘who is the donor of the trace?’) but also those relating to activitity level (i.e. ‘how did the DNA get there?’). The answers to these questions are usually formulated as the probability of the evidence under alternative scenarios. As activity level questions are part of investigative and legal considerations it is of paramount importance that expert witnesses are provided with knowledge and tools to address these questions.To answer such questions within a probabilistic framework, empirical data is needed to estimate probabilities of transfer, persistence and recovery of DNA as well as background levels of DNA on everyday objects. There is a paucity of empirical data on these topics, but the number of studies is increasing both through in-house experiments and experimental data published in international scientific journals.Laboratories that conduct such studies all use different experimental setups, trace recovery strategies and techniques and DNA analysis systems and equipment. It is essential for the forensic genetics community in general to establish whether the data generated by different labs are in concordance, and can therefore be readily used by the forensic community.Moreover, if existing data and data generated from future experiments are made available to the (forensic) community, knowledge is needed on the key factors that underlie potential interlaboratory variation.The aims and objectives of this ENFSI Monopoly 2013 project are to conduct a study of methodologies and data from different laboratories and to assess the comparability of the scientific data on transfer, persistence and recovery of DNA. This comparison will allow us to identify key factors that underlie potential variation. This information will be used to setup guidelines to enable sharing and database-storage of relevant scientificdata. This will improve the ability of forensic scientists and other professionals of the Criminal Justice System to give evidence-based answers to questions that relate to the activity level of the crime under investigation.
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| 6. |
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| 7. |
- Albinsson, L., et al.
(författare)
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Mixed DNA profiles from single-donors
- 2015
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Ingår i: Abstract book, 7<sup>th</sup> European Academy of Forensic Science, EAFS, Prag, Tjeckien, 2015. ; , s. 538-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Mosaicism and chimerism in individuals can complicate the interpretation and even lead to misinterpretation of DNA profiles in forensic casework. If a person has different DNA profiles in different tissue types, i.e. a true chimaera, wrongful exclusions can be made. Additionally, mixed chimaeras can have DNA profiles that may be mistaken for mixtures. We have set-up automatic DNA databasing processes to handle atypical single-donor DNA profiles, i.e. profiles having one or several “extra” alleles.Studying all reference samples analysed at NFC from 2006 until spring 2014, 2‰ of the samples showed atypical DNA profiles. To be able to set routines for handling these DNA profiles, each one was manually searched in CODIS with adjusted settings, to evaluate the frequency of false-positive hits. To tag these profiles in LIMS a new result status was implemented. Additionally, all such DNA profiles must be confirmed by analysing at least two discrete samples. In LIMS, the results are manually recorded to compose of all alleles from the samples from a suspect, i.e. containing most possible genetic information. LIMS automatically categorises the atypical DNA profiles with a special CODIS index, called “Multi-allelic offender”. The first time an atypical profile is searched, the matches are manually investigated. If a match is false, its disposition will be set to “no match” to prevent this from occurring in future searches. Automatic searches will then be performed in every day routine with moderate stringency, allowing the atypical DNA profile to match either a genotype or a mixture. If the match is true, a match-report will be created and sent to the police from the LIMS.
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| 8. |
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| 9. |
- Albinsson, Linda, et al.
(författare)
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SKL byter DNA-kit
- 2011
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Ingår i: Kriminalteknik. - Linköping : SKL. ; :1, s. 4-5
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 10. |
- Albinsson, Linda, et al.
(författare)
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Swedish population data and concordance for the kits PowerPlexÒ ESX 16 System, PowerPlexÒ ESI 16 System, AmpFlSTRÒ NGMTM, AmpFlSTRÒ SGM PlusTM and Investigator ESSplex
- 2011
-
Ingår i: Forensic Science International. - Clare, Irland : Elsevier. - 1872-4973 .- 1878-0326. ; 5:3, s. e89-e92
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The European Standard Set of loci (ESS) has been extended with five additional short tandem repeat (STR) loci following the recommendations of the European Network of Forensic Science Institutes (ENFSI) and the European DNA Profiling Group (EDNAP) to increase the number of loci routinely used by the European forensic community. Subsequently, a new extended Swedish population database, based on 425 individuals, has been assembled using the new STR multiplex kits commercially available.Allele frequencies and statistical parameters of forensic interest for 15 autosomal STR loci (D3S1358, TH01, D21S11, D18S51, D10S1248, D1S1656, D2S1338, D16S539, D22S1045, vWA, D8S1179, FGA, D2S441, D12S391 and D19S433) were obtained from the analysis of the PowerPlex® ESX 16 System kit (Promega Corporation, USA). According to the data no evidence of deviations from Hardy–Weinberg equilibrium was found. The observed heterozygosity varies between 0.755 (TH01) and 0.892 (D1S1656). The power of discrimination was smallest for D22S1045 (0.869) and largest for D1S1656 (0.982) while the power of exclusion was smallest for TH01 (0.518) and largest for D1S1656 (0.778).A concordance study was performed on the five amplification systems: PowerPlex® ESX 16 System, PowerPlex® ESI 16 System (Promega Corporation, USA), AmpFlSTR® NGM™, AmpFlSTR® SGM Plus™ (Applied Biosystems, USA) and Investigator ESSplex (Qiagen, Germany) to reveal null alleles and other divergences between the kits. For the 425 DNA profiles included, AmpFlSTR® NGM™ revealed two null alleles, AmpFlSTR® SGM Plus™ revealed one, and Investigator ESSplex revealed a micro-variant, while the rest of the alleles showed full concordance between the kits tested.
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| 11. |
- Albinsson, L., et al.
(författare)
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Verification of alleles by using peak height thresholds and quality control of STR profiling kits
- 2011
-
Ingår i: Forensic Science International: Genetics, Supplement Series. - : Elsevier. - 1875-1768. ; 3:1, s. e251-e252
-
Tidskriftsartikel (refereegranskat)abstract
- In the autumn of 2010 SKL performed in-house validation of PowerPlex ESX 16 System (Promega). As the validation showed that very low amounts of DNA (∼10 pg) may provide correct allele callings (peaks above 50 rfu), we investigated the linear range, i.e., the interval of DNA amounts where a profile is well balanced and does not contain drop-outs and/or drop-ins. The linear range as indicated by our results is approximately from 0.5 ng (manufacturer's recommendation) to 2.0 ng of DNA. As minute DNA amounts may be detected using the kit, extra care needs to be taken not to report a contaminant allele as a part of the correct profile. A way to verify the correctness of a single donor profile in routine analysis, without using duplicate analysis, is to use conservative peak height thresholds. We determine STR marker specific peak height thresholds for each new lot of DNA profiling kits, based on the results from three different tests: heterozygote balance, signal intensity and repeatability, and PCR inhibitor tolerance. The tests also serve to verify the quality of the kit lot. Generally, the peak height thresholds vary between 200 and 250 rfu for heterozygote alleles, with doubled values used for homozygotes.
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| 12. |
- Albinsson, L., et al.
(författare)
-
Verification of alleles by using peak height thresholds and quality control of STR profiling kits
- 2011
-
Ingår i: Book of Abstracts. ; , s. 134-
-
Konferensbidrag (refereegranskat)abstract
- In the autumn of 2010 SKL performed in-house validation of PowerPlex ESX 16 System (Promega). As the validationshowed that very low amounts of DNA (< 10 pg) may provide correct allele callings (peaks above 50 rfu),we investigated the linear range, i.e., the interval of DNA amounts where a profile is well balanced and doesnot contain drop-outs and/or drop-ins. The linear range as indicated by our results is approximately from 0.5ng (manufacturer’s recommendation) to 2.0 ng of DNA. Profiles generated by less than 0.5 ng contained intralocus imbalances and/or drop-outs. Above 2.0 ng “bleed through” occurs due to overload of template-DNA.A way to verify the correctness of a profile, without knowing anything about the condition of the template-DNA, is to use peak height thresholds adjusted to each marker and batch of kits used. SKL performs a qualitycontrol and adjust thresholds for each batch of kits. Three main tests are performed; detection limit, inhibitortolerance and signal repeatability. The detection limit is examined to identify at which concentration intralocus imbalances and drop-outs start to increase. The ability to overcome inhibition is checked by analysingvarying amounts of blood extracted with Chelex. Finally a set of replicates of control DNA is amplified (0.5 ngtemplate-DNA) to calculate the mean peak height and standard deviation at each locus. Generally, the peakheight thresholds vary between 200 and 250 rfu for heterozygote peaks. To verify allelic peaks below the setpeak height thresholds, SKL uses consensus analysis.
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| 13. |
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| 14. |
- Ansell, Ricky, et al.
(författare)
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Centrum för genetisk identifiering
- 2014
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Ingår i: Kriminalteknik. - Linköping : Statens Kriminaltekniska Laboratorium. - 1653-6169. ; :1, s. 21-
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 15. |
- Ansell, Ricky, et al.
(författare)
-
Contamination monitoring in the forensic DNA laboratory and a simple graphical model for unbiased EPG classification
- 2011
-
Ingår i: Book of Abstracts. ; , s. 199-
-
Konferensbidrag (refereegranskat)abstract
- In this work we present a procedure for contamination monitoring in a trace search and recovery area and agraphical classification model. The recent launch of more sensitive and robust amplification kits increases thepossibility to detect minute amounts of trace DNA. As a consequence this enhances our need to establish eliminationdatabases and demands for an increased awareness on how to avoid contamination. DNA contaminatingthe evidence somewhere along the forensic process has the potential to destroy the evidence or totally confuseand mislead the crime investigation. In the forensic laboratory specific areas are designated for different partsof the process: trace search and recovery, pre-PCR, post-PCR etc. Work procedures and cleaning routines areadapted to minimise the risk of contamination. Monitoring presence of DNA in the laboratory environment, onspecific surfaces or instruments of interest, is one way to assess these risks and will in addition increase ourknowledge on how to improve cleaning routines and behaviour in the lab. A monitoring process needs to someextent be standardised in order to become unbiased and independent on an individual level, regarding bothwhere and how samples are taken and how the results are classified. The graphical model constitutes a lineartransformation of a three-dimensional “credit system” based on alleles, markers and peak heights, into a twodimensional classification. The standardisation allows results to be compared over time, and if applied to otherwork-areas comparison between different parts of the process will be possible.
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| 16. |
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| 17. |
- Ansell, Ricky, et al.
(författare)
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DNA-analyser inom brottsbekämpningen
- 2016
-
Ingår i: Skurk, sjuk eller släkt?. - Stockholm : Stiftelsen för strategisk forskning. - 9189206657 - 9789189206656 ; , s. 18-27
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Idag räcker det med DNA från enstaka celler för att kunna få fram en DNA-profil som kan jämföras med per-soner eller andra DNA-spår. En DNA-träff mot ett biologiskt spår kan utgöra en mycket stark bevisning och vara avgörande för en fällande dom. DNA-teknik gör det möjligt att analysera och ta fram en DNA-profil för de allra flesta typer av humana biologiska spår som avsatts i samband med brott, såsom blod, sperma, vaginalsekret, saliv, hår och ”kontaktspår”. Teknikerna har med åren utvecklats och förfinats. På senare år har också det internationella utbytet av DNA-profiler ökat samtidigt som fortsatt teknik- och metodutveckling banar väg för fördjupade analy-ser som kan bidra till att klara upp brott. Det kan handla om att utifrån DNA-spår ringa in ungefärlig ålder, ursprung, hårfärg, ögonfärg och kroppsstorlek på en misstänkt gärningsman
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| 18. |
- Ansell, Ricky
(författare)
-
Dna-möte på NFC
- 2015
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Ingår i: Kriminalteknik. - Linköping, Sverige : Nationellt forensiskt centrum.
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 19. |
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| 20. |
- Ansell, Ricky
(författare)
-
Dna-spår betydelsefulla i sexualbrottsärenden
- 2014
-
Ingår i: Kriminalteknik. - Linköping : Statens kriminaltekniska laboratorium. - 1653-6169. ; :3, s. 16-17
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 21. |
- Ansell, Ricky
(författare)
-
Forensisk dna-kongress i Krakow – ISFG 2015
- 2015
-
Ingår i: Kriminalteknik. - Linköping, Sverige : Nationellt forensiskt center - NFC. - 1653-6169.
-
Tidskriftsartikel (populärvet., debatt m.m.)
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| 22. |
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| 23. |
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| 24. |
- Ansell, Ricky
(författare)
-
Genetiska fantombiler
- 2011
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Ingår i: Kriminalteknik. - Linköping : SKL. - 1653-6169. ; :1, s. 6-7
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 25. |
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| 26. |
- Ansell, Ricky
(författare)
-
Internal quality control in forensic DNA analysis
- 2013
-
Ingår i: Accreditation and Quality Assurance. - : Springer Berlin/Heidelberg. - 0949-1775 .- 1432-0517. ; 18:4, s. 279-289
-
Tidskriftsartikel (refereegranskat)abstract
- The trail from initial evidence examination to a DNA profile reported to match a suspect is long and complex. The different nature and great variability in the biological and DNA evidence to be recovered and analyzed, add to this complexity. Internal quality controls play an important role in maintaining a high-quality performance in daily forensic biology and DNA profiling practice. In many cases are empirical rather than analytical approaches adopted. Obviously, despite the fact of being necessary, the internal quality controls performed still need to be kept rational at a limited, yet acceptable level. Quality control from a forensic biology and DNA profiling horizon has a wider context and does not only concern obvious fit-for-purpose verifications of analytical processes, chemicals, or reagents in daily routine practice. It also includes control on computerized laboratory management and expert systems, laboratory environmental DNA monitoring, and the use of elimination DNA databases. In addition, a structured recording and handling of non-conformances and “near failures” is essential. Proper management of the non-conformances supports continuous quality improvements by learning from the errors occurring in daily practice. High transparency of non-conformances is important not only for internal improvements, but also for the criminal justice system as well as to maintain public confidence and trust. Together the quality controls used aim at maintaining evidence and DNA sample integrity and to accomplish correct results and interpretations by verifying that methods used data transfers and interpretations made are correct and performed according to validated and accredited conditions.
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| 27. |
- Ansell, Ricky, et al.
(författare)
-
Interpretation of DNA Evidence: Implications of Thresholds Used in the Forensic Laboratory
- 2014
-
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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| 28. |
- Ansell, Ricky
(författare)
-
Kvalitetsmöte med Forensic Science Regulator
- 2014
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Ingår i: Kriminalteknik. - Linköping : Statens Kriminaltekniska Laboratorium. - 1653-6169. ; :1, s. 22-23
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 29. |
- Ansell, Ricky, 1967-, et al.
(författare)
-
Läkares säkring av bevis efter sexualbrott viktig del i rättsprocessen
- 2008
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Ingår i: Läkartidningen. - 0023-7205 .- 1652-7518. ; 105:9, s. 634-637
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Tidskriftsartikel (refereegranskat)abstract
- In cases of sexual assault, physical evidence can be of crucial importance for a conviction. Intimate samples initially collected by a physician can prove to be the only supporting evidence for the prosecution to present at court proceedings. New analysis techniques and methods have increased the positive outcome of the samples collected. This in combination with increased use of national criminal DNA databases results in the solving of sexual crimes with unknown perpetrators. The use of standardised rape care kits facilitates the work of the physician in performing an adequate sampling procedure. The Swedish "rape care kit" has been developed and updated in response to experience gained and new possibilities.
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| 30. |
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| 31. |
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| 32. |
- Ansell, Ricky
(författare)
-
Ny teknik för identifiering utan DNA
- 2011
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Ingår i: Kriminalteknik. - Linköping : SKL. - 1653-6169. ; :3, s. 32-
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 33. |
- Ansell, Ricky
(författare)
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Nytt på dna-området
- 2013
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Annan publikation (populärvet., debatt m.m.)
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| 34. |
- Ansell, Ricky, et al.
(författare)
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Phadebas® Press test and the presence of amylases in different body fluids deposited on textile
- 2011
-
Ingår i: Book of Abstracts. ; , s. 136-
-
Konferensbidrag (refereegranskat)abstract
- In forensic DNA casework saliva stains with epithelial cells can be very useful even presenting the key evidence.Tests for amylase activity, like Phadebas® Press test, help locate stains and indicate presence of saliva. Sensitivityis high, with positive amylase tests obtained prior to detectable levels of DNA and saliva diluted to 1:100readily generate a positive reaction with Phadebas® Press test for presence of amylase. The salivary amylaseactivity varies on individual basis over time as well as it does between individuals. In addition some individualssecrete high levels of amylases [1,2]. However, amylases are present in other body fluids as well, generally toomuch lower levels than saliva. Due to sensitivity of amylase tests there is a potential interference by otherfluids when using them to verify the presence of saliva. Other studies also demonstrate that e.g. faeces can givepositive reactions.For underwear the presence of several different body fluids might have natural causes, including vaginal secretions,(menstrual) blood, urine, faeces, as well as semen and saliva. Here we present the use of Phadebas® Presstest on underwear with naturally deposited body fluids and single source body fluid mock samples including oneindividual with higher levels of amylase activity. Our results and implications are discussed. [1] J. Hedman, E. Dalin, B. Rasmusson, R. Ansell (2011). Forensic Science International; Genetics, 5, 194–198. [2] J. Hedman, K. Gustavsson, R. Ansell (2008). Forensic Science International; Genetics Supplement Series, 1(1), 430–432.
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| 35. |
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| 36. |
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| 37. |
- Ansell, Ricky
(författare)
-
Sexualbrottsärenden på SKL
- 2008
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Ingår i: Kriminalteknik. - Linköping : SKL. - 1653-6169. ; :4, s. 12-17
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 38. |
- Ansell, Ricky, et al.
(författare)
-
Snabbanalysinstrumentet RapidHIT på SKL
- 2014
-
Ingår i: Kriminalteknik. - Linköping : Statens Kriminaltekniska Laboratorium. - 1653-6169. ; :1, s. 18-19
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
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| 39. |
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| 40. |
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| 41. |
- Ansell, Ricky, et al.
(författare)
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Swedish Legislation Regarding Forensic DNA Elimination Databases
- 2016
-
Ingår i: Forensic Science Policy & Management: An International Journal . - : Taylor & Francis Group. - 1940-9044 .- 1940-9036. ; 7:1-2, s. 20-36
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Tidskriftsartikel (refereegranskat)abstract
- Evidence contaminated with DNA from staff, police, and other individuals can have a dramaticimpact on an investigation and can mislead police inquiries. Forensic DNA elimination databases(EDB) are used to minimize the risks associated with DNA contamination. Central issues withmaintaining such databases include the basis for sample collection, sample, and profile integrity, aswell as retention times, database access, and procedures when a database match occurs. Followingyears of discussion, debate, and the use of an “in house” EDB at the Swedish National ForensicCentre (NFC), these issues have now been resolved by passing legislation on DNA EDB. According tothe legislation, sampling for EDB purposes is mandatory for certain forensic professionals, as well asfor other individuals who need access to the premises handling DNA evidence. In the event of adatabase match, the match can only be reviewed and evaluated for quality purposes and the nameof the donor cannot be disclosed to the crime inquiry. Thus, as a consequence, if a contaminationevent is not the probable cause the legal limitation opens for impunity for individuals included inthe database.KEYWORDSContamination; DNA;elimination database;forensic science; legislationIntroduction
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| 44. |
- Benschop, Corina C G, et al.
(författare)
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Results of an inter and intra laboratory exercise on the assessment of complex autosomal DNA profiles.
- 2017
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Ingår i: Science & justice. - : Elsevier. - 1355-0306 .- 1876-4452. ; 57:1, s. 21-27
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Tidskriftsartikel (refereegranskat)abstract
- The interpretation of complex DNA profiles may differ between laboratories and reporting officers, which can lead to discrepancies in the final reports. In this study, we assessed the intra and inter laboratory variation in DNA mixture interpretation for three European ISO17025-accredited laboratories. To this aim, 26 reporting officers analyzed five sets of DNA profiles. Three main aspects were considered: 1) whether the mixed DNA profiles met the criteria for comparison to a reference profile, 2) the actual result of the comparison between references and DNA profiling data and 3) whether the weight of the DNA evidence could be assessed. Similarity in answers depended mostly on the complexity of the tasks. This study showed less variation within laboratories than between laboratories which could be the result of differences between internal laboratory guidelines and methods and tools available. Results show the profile types for which the three laboratories report differently, which informs indirectly on the complexity threshold the laboratories employ. Largest differences between laboratories were caused by the methods available to assess the weight of the DNA evidence. This exercise aids in training forensic scientists, refining laboratory guidelines and explaining differences between laboratories in court. Undertaking more collaborative exercises in future may stimulate dialog and consensus regarding interpretation. For training purposes, DNA profiles of the mixed stains and questioned references are made available.
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| 45. |
- Boiso, Samuel, et al.
(författare)
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RapidHIT for the purpose of stain analyses – An interrupted implementation
- 2017
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Ingår i: Forensic Science International. - : Elsevier. - 1875-1768 .- 1875-175X. ; 6:Supplement C, s. e589-e590
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Tidskriftsartikel (refereegranskat)abstract
- Rapid DNA instruments have in recent years been developed, enabling analysis of forensic samples with a minimum of human intervention. Initially intended for fast handling of reference samples, such as samples from suspects in booking suites, attention shifted to include crime scene samples. The aim of this study was to determine whether or not the RapidHIT System (IntegenX) is fit for crime scene samples. The first runs gave very poor results, which was found to be due to an incorrect firmware setting leading to no or just minute amounts of amplicons being injected for electrophoresis. After solving this problem, 28 full runs (seven samples each) applying NGM SElect Express were performed comprising various amounts of blood on cotton swabs. Six of the runs failed completely, four due to cartridge leakage and in two runs the PCR mix was not injected. For 155 samples with 1–5ΌL blood (volumes for which complete DNA profiles are expected), 119 samples (77%) gave complete DNA profiles. Among the most serious failures were incorrect allele calling and leakage of DNA extract or PCR product. Other general issues were failure to export results, anode motor breakdown and broken capillary array. Due to the encountered problems with software, hardware and cartridges, together with the low success rate, it was decided not to continue towards implementation of the RapidHIT System in casework.
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| 46. |
- Chaitanya, Lakshmi, et al.
(författare)
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Collaborative EDNAP exercise on the IrisPlex system for DNA based prediction of human eye colour
- 2014
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Ingår i: Forensic Science International. - : Elsevier. - 1872-4973 .- 1878-0326. ; 11, s. 241-251
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Tidskriftsartikel (refereegranskat)abstract
- The IrisPlex system is a DNA-based test system for the prediction of human eye colour from biological samples and consists of a single forensically validated multiplex genotyping assay together with a statistical prediction model that is based on genotypes and phenotypes from thousands of individuals. IrisPlex predicts blue and brown human eye colour with, on average, >94% precision accuracy using six of the currently most eye colour informative single nucleotide polymorphisms (HERC2 rs12913832, OCA2 rs1800407, SLC24A4 rs12896399, SLC45A2 (MATP) rs16891982, TYR rs1393350, and IRF4 rs12203592) according to a previous study, while the accuracy in predicting non-blue and non-brown eye colours is considerably lower. In an effort to vigorously assess the IrisPlex system at the international level, testing was performed by 21 laboratories in the context of a collaborative exercise divided into three tasks and organised by the European DNA Profiling (EDNAP) Group of the International Society of Forensic Genetics (ISFG). Task 1 involved the assessment of 10 blood and saliva samples provided on FTA cards by the organising laboratory together with eye colour phenotypes; 99.4% of the genotypes were correctly reported and 99% of the eye colour phenotypes were correctly predicted. Task 2 involved the assessment of 5 DNA samples extracted by the host laboratory from simulated casework samples, artificially degraded, and provided to the participants in varying DNA concentrations. For this task, 98.7% of the genotypes were correctly determined and 96.2% of eye colour phenotypes were correctly inferred. For Tasks 1 and 2 together, 99.2% (1875) of the 1890 genotypes were correctly generated and of the 15 (0.8%) incorrect genotype calls, only 2 (0.1%) resulted in incorrect eye colour phenotypes. The voluntary Task 3 involved participants choosing their own test subjects for IrisPlex genotyping and eye colour phenotype inference, while eye photographs were provided to the organising laboratory and judged; 96% of the eye colour phenotypes were inferred correctly across 100 samples and 19 laboratories. The high success rates in genotyping and eye colour phenotyping clearly demonstrate the reproducibility and the robustness of the IrisPlex assay as well as the accuracy of the IrisPlex model to predict blue and brown eye colour from DNA. Additionally, this study demonstrates the ease with which the IrisPlex system is implementable and applicable across forensic laboratories around the world with varying pre-existing experiences.
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| 47. |
- Digréus, P., et al.
(författare)
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Contamination monitoring in the forensic DNA laboratory and a simple graphical model for unbiased EPG classification
- 2011
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Ingår i: Forensic Science International: Genetics, Supplement Series. - : Elsevier. - 1875-1768. ; 3:1, s. e299-e300
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Tidskriftsartikel (refereegranskat)abstract
- Monitoring presence and level of background DNA in forensic DNA laboratory environments can be used to control work routines and cleaning procedures and to follow changes in these, as well as being an indicator for increased/decreased contamination risk. Previous monitoring routines as sampling and interpretation have not been standardised, making it difficult to compare between different sampling events and observe potential trends. Factor analysis was used to generate a simple graphical classification model for unbiased ranking of electropherograms, which can be modified according to user's need, taking into account number of detected alleles, markers and peak height.
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| 48. |
- Dufva, Charlotte, et al.
(författare)
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DNA profiles obtained from urine in snow
- 2019
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Ingår i: Forensic Science International. - : ELSEVIER IRELAND LTD. - 1875-1768 .- 1875-175X. ; 7:1, s. 544-545
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Tidskriftsartikel (refereegranskat)abstract
- Urine can be a potential important source of evidence when occurring at crime scenes. In case of outdoor scenes including snow a yellow colour could indicate the existence of human urine. In an effort to be able to investigate urine as a crime scene sample we have evaluated protocols for analysing DNA from urine in snow. Two different tests were performed with a smaller and a larger volume of urine dispensed on snow. The tubes were put into a freezer to mimic winter conditions. A Urine Preservative was added to some of the samples. DNA profiles were compared between samples extracted using a Urine DNA Isolation Kit and samples extracted with a Chelex-based method. In addition, a test was performed with the aim to mimic a potential crime scene. With a smaller volume of urine the best quality DNA profiles were obtained using the Urine DNA Isolation Kit without the Urine Preservative. When a larger volume of urine was handled and in the crime scene setup, there were no clear difference between the two extraction methods. Instead, the variation observed was between individuals.
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| 49. |
- Foreberg, Christina, et al.
(författare)
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High-throughput DNA extraction of forensic adhesive tapes
- 2016
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Ingår i: Forensic Science International. - : Elsevier. - 1872-4973 .- 1878-0326. ; 24, s. 158-163
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Tidskriftsartikel (refereegranskat)abstract
- Tape-lifting has since its introduction in the early 2000's become a well-established sampling method in forensic DNA analysis. Sampling is quick and straightforward while the following DNA extraction is more challenging due to the "stickiness", rigidity and size of the tape. We have developed, validated and implemented a simple and efficient direct lysis DNA extraction protocol for adhesive tapes that requires limited manual labour. The method uses Chelex beads and is applied with SceneSafe FAST tape. This direct lysis protocol provided higher mean DNA yields than PrepFiler Express BTA on Automate Express, although the differences were not significant when using clothes worn in a controlled fashion as reference material (p=0.13 and p=0.34 for T-shirts and button-down shirts, respectively). Through in-house validation we show that the method is fit-for-purpose for application in casework, as it provides high DNA yields and amplifiability, as well as good reproducibility and DNA extract stability. After implementation in casework, the proportion of extracts with DNA concentrations above 0.01ng/μL increased from 71% to 76%. Apart from providing higher DNA yields compared with the previous method, the introduction of the developed direct lysis protocol also reduced the amount of manual labour by half and doubled the potential throughput for tapes at the laboratory. Generally, simplified manual protocols can serve as a cost-effective alternative to sophisticated automation solutions when the aim is to enable high-throughput DNA extraction of complex crime scene samples.
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| 50. |
- Forsberg, C., et al.
(författare)
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Reference material for comparison of different adhesive tapes for forensic DNA sampling : -
- 2015
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Ingår i: Abstracts ISFG. ; , s. 267-268
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Konferensbidrag (refereegranskat)abstract
- Tape-lifting is an efficient method for collecting traces of cellular material from fabrics. Since 2006, an in-house adhesive tape has been used in casework at the Swedish National Forensic Centre, Linköping. Although this tape gives good DNA yields, we aim to replace it with a commercial tape to save cost and labor. In order to enable a fair comparison between different adhesive tapes, we have developed and evaluated a method for production of relevant reference material. One person, known to be a good shedder, wore identical long-sleeved T-shirts under controlled circumstances, and trace recovery was systematically performed with the in-house tape (3 T-shirts, total of 24 samples). Each sample was DNA extracted (Chelex) and quantified (Quantifiler Human DNA Quantification kit) to find the normal variation within the reference material.The DNA recovery differed considerably between samples, with obtained DNA concentrations between 0.010-0.481 ng/μL (mean: 0.083, standard deviation: 0.116 ng/μL). Applying such a reference material for comparison between two commercial tapes and our in-house tape resulted in mean DNA recoveries plus/ minus one standard deviation of 0.013±0.006 ng/μL (Scenesafe FAST Box), 0.012±0.007 ng/μL (Touch Tape), and 0.023±0.013 ng/μL (in-house tape).The in-house tape gave statistically significant higher yield compared to Touch Tape (p<0.05), but for Scenesafe the difference was not significant. Shedding of cells to worn clothes is a random process. Having a systematically prepared, casework-like reference material with known variation is therefore vital for comparative studies of tapes.
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