Ultrasonic assessment is a new approach to assess both quality and density. Two ultrasonic parameters are measured on the os calcis: the attenuation or broadband ultrasound attenuation (BUA) and the velocity or speed of sound (SOS). The interunit variations in vitro and in vivo of an ultrasound instrument, the Lunar Achilles system, used in a French multicenter study named EPIDOS, were calculated and the stability of these instruments over a 12-month period was evaluated. A third parameter called "stiffness index," calculated from the SOS and BUA, was also used in this study. The average CV in vitro for the BUA and SOS was 0.92% and 0.12%, respectively, and the average CV in vivo for the BUA, the SOS, and the stiffness index was 1.83%, 0.23%, and 1.9%, respectively. The interunit (or inter-machines) variations were calculated by a one-way analysis of variance. We detected small but significant measurement differences among centers on a phantom for both SOS (maximum significant difference 0.4%) and stiffness (maximum significant difference 3.5%) but not for BUA. Similar differences were found in vivo. The precision over 12 months of the interunit variations in vitro was evaluated by measuring a single phantom traveling from one center to another several times. The range of the CV for the BUA (1.54-0.51%), for the SOS (0.25-0.14%), and for the stiffness index (2.26-1.10%) are explained in part by technical failures. The variation among the five Achilles was estimated by the combined CV which was 1.42% for the BUA, 0.32% for the SOS, and 2.33% for the stiffness index. In conclusion, our findings indicate that equipment from one manufacturer appears to be consistent between machines for the BUA, but not completely for the SOS. The results for this stiffness index are necessarily influenced by both SOS and BUA. The short-term and long-term interunit precision is good, both in vitro and in vivo. Such results provide increased confidence in multicenter clinical trials where ultrasonic data are pooled.
Keywords: GSR SEM/EDX NAA Chemical ballistic Scientific Police of Algeria a
b s t r a c tThis work is realized in view to determine appropriate techniques for the revelation of mineral gun shoot residues. Picked up from the crime scene, these indicial traces are used as material proofs for helping and guiding judicial investigations. As achievement of this process, two (02) technics were employed for mineral gun shoot residues, namely; Neutron Activation Analysis, and scanning electron microscopy/EDX. Samples of metallic powder residue were realized after several shoots by different kind of weapons with local and foreign ammunitions. So, this study was undertaken to develop chemical ballistic specialty in order to improve forensic investigations and drive benefit to Technical and ScientificPolice of Algeria to be use for judicial investigation.It turns out that the SEM/EDX method is more adequate to this type of investigation, despite the high sensitivity of the NAA. This is stated; NAA remains a complementary methods.
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