Reduce optimisation time and effort: Taguchi experimental design methods

Development and validation of new methods and technologies frequently require long periods of time and high costs to determine the optimal system. A commonly used approach to optimisation is the factorial method, where each variable is tested at every level of the other variables. An alternative approach is to modify the experimental design using a multifactorial approach. The Taguchi design method utilises orthogonal arrays, which distribute the variables in a balanced manner, thus greatly reducing the number of experiments required. We applied the Taguchi experimental design method to PCR optimisation, and significantly reduced the number of reactions required to create highly successful reactions. We found the Taguchi design method a valuable tool for the optimisation of multifactor experiments.     

Haftung für Baumwurzeln im Kanal (Anm.: Franz Otto)

Ohne Zusammenfassung     

The consumer racial profiling experiences of Black students at historically Black colleges and universities: An exploratory study

This article examines consumer racial profiling among Black students at historically Black colleges and universities (HBCUs). Consumer Racial Profiling (CRP) is when store employees target a shopper or shoppers for discriminatory treatment based on their race or ethnicity. The research revealed that students have been exposed to a variety of CRP practices (e.g., being followed around, etc.). Even though they have been victims of CRP, many of the students did not report doing anything about it. Multivariate analyses were conducted to determine the most significant predictors of both having reported being a victim of CRP and also reporting the incident. The article concludes arguing that victims of CRP must report the incidents—if they are to be minimized, or in the best-case scenario, eliminated. In addition, the authors argue that criminologists should pay more attention to both CRP and the experiences and views of students at HBCUs.     

Haplotype diversity in human mitochondrial DNA hypervariable regions I–III in the city of Caracas (Venezuela)

In order to expand the database of variable DNA for forensic identification purposes in Venezuela, we analyzed the sequence polymorphisms of mitochondrial DNA (mtDNA) hypervariable regions (HVR) I–III from 100 unrelated individuals from the city of Caracas, using PCR amplification and fluorescent-based capillary electrophoresis sequencing method. Dominant haplogroups corresponded to Native Americans followed by African ones. The inclusion of HVR III although useful for sub-haplogroup assignation, added little to the discrimination capacity of our database.     

DNA recovery after sequential processing of latent fingerprints on copy paper

Forensic examiners must determine whether both latent fingerprint development and DNA profiling can be performed on the same area of an evidence item and, if only one is possible, which examination offers the best chance for identification. Latent fingerprints can be enhanced by targeting different components of fingerprint residues with sequential chemical treatments. This study investigated the effects of single-reagent and sequential latent fingerprint development processes on downstream DNA analysis to determine the point at which latent fingerprint development should be stopped to allow for DNA recovery. Latent fingerprints deposited on copy paper by one donor were developed using three sequential processes: 1,8-diazafluoren-9-one (DFO) → ninhydrin → physical developer (PD); 1,2-indanedione-zinc (IND-Zn) → ninhydrin → PD; and IND-Zn → ninhydrin → Oil Red O (ORO) → PD. Samples were examined after the addition of each chemical treatment. DNA was collected with cotton swabs, extracted, quantified, and amplified. DNA yields, peak heights, number of alleles obtained, and percentage of DNA profiles eligible for CODIS upload were examined. DNA profiles were obtained with varying degrees of success, depending on the number and type of treatments used for latent fingerprint development. The treatments that were found to be the least harmful to downstream DNA analysis were IND-Zn and IND-Zn/laser, and the most detrimental treatments were DFO, DFO/laser, and PD. In general, as the number of treatments increase, the opportunities for DNA loss or damage also increase, and it is preferable to use fewer treatments when developing latent fingerprints prior to downstream DNA processing.