Numerical classification of curvilinear structures for the identification of pistol barrels

This paper demonstrates a numerical pattern recognition method applied to curvilinear image structures. These structures are extracted from physical cross-sections of cast internal pistol barrel surfaces. Variations in structure arise from gun design and manufacturing method providing a basis for discrimination and identification. Binarised curvilinear land transition images are processed with fast Fourier transform on which principal component analysis is performed. One-way analysis of variance (95% confidence interval) concludes significant differentiation between 11 barrel manufacturers when calculating weighted Euclidean distance between any trio of land transitions and an average land transition for each barrel in the database. The proposed methodology is therefore a promising novel approach for the classification and identification of firearms.     

IMPLEMENTING CHANGE IN HEALTH SYSTEMS: MARKET REFORMS IN HEALTH SYSTEMS IN THE UNITED KINGDOM,SWEDEN AND THE NETHERLANDS

IMPLEMENTING CHANGE IN HEALTH SYSTEMS: MARKET REFORMS IN HEALTH SYSTEMS IN THE UNITED KINGDOM, SWEDEN AND THE NETHERLANDS
Michael I. Harrison
Sage, 2004, 256 pp., £21.99 (pb) ISBN: 0761961763     

Developing Sexual Self-Efficacy Beliefs During Adolescence: Do Health Teachers Really Matter?

Teacher attitudes and instructional strategies impact success of human sexuality programs. Limited prior research has examined the relations of teachers’ attitudes and instruction to the development of adolescents’ sexual self-efficacy beliefs. This study examined how adolescents’ perceptions of their health teachers (i.e., teacher value of content, teacher affinity, teacher caring for students) predict changes in efficacy beliefs related to HIV/STD and pregnancy prevention, and if perceptions of mastery goal structure predicted adaptive efficacy beliefs. Data were collected in 4 Midwestern/Appalachian high schools in health class where the delivery of a 14-lesson sexual health curriculum occurred. Participants included 561 students (50.4% 9^th graders, 43.5% female, 56.3% White, 53.7% did not have a current romantic partner, and 59.7% had previously not engaged in sexual activity). The findings indicate students’ perceptions of teachers valuing the content predicted perceptions of mastery goal structure for all sexual self-efficacy beliefs: learning efficacy, condom negotiation efficacy, refusal self-efficacy, and situational self-efficacy. Students who perceive a mastery goal structure in health class, and who feel their teachers value learning about HIV/STD and pregnancy prevention, are likely to experience positive adaptive self-efficacy beliefs related to sexual health, ultimately leading to behaviors indicative of decreased STDs among teenagers and safe sexual practices, such as abstinence, the use of a condom, and saying “no” to having sex.

     

Sequenced allelic ladders and population genetics of a new STR multiplex system

The advent of PCR technology and use of short tandem repeat (STR) loci improves throughput and reduces costs whilst a high level of discrimination can be achieved. A new system, comprising seven STRs, was developed to compliment the existing systems. This paper describes the preparation of allelic ladders of the most commonly observed alleles of a new STR multiplex system (third generation; TGM multiplex); all alleles have been sequenced. Meioses studies estimated a mutation rate of 0-0.4% across loci. Statistical independence was investigated by employing exact tests; chi(2)-tests and excess homozygosity tests. The results demonstrated that the allele proportions do not differ from those expected and that there was no consequential dependence between loci. The discriminating power of the system was examined using 295 Caucasian, 140 Afro-Caribbean and 212 Asian unrelated samples, and was found to be approximately 1 in 50 million, 1 in 85 million and 1 in 20 million for each of these groups, respectively.     

Validation of the AMPFlSTR SGM plus system for use in forensic casework

The AMPFlSTR((R)) SGM Plus system is a commercially available STR multiplex produced by Applied Biosystems, a division of Perkin Elmer, Foster City, California, USA that supersedes SGM. The multiplex contains the six SGM loci, amelogenin and four additional loci. These additional loci are D3S1358, D19S433, D16S539 and D2S1338. Consequently, the match probability is significantly improved (conservatively quoted as 1 in 10(9) for reporting a full profile match). The system was subjected to validation. For example, ageing and degradation studies demonstrated semen stains to be the most stable evidence type, whereas buccal scrapes were the least stable. An apparent rise in the sensitivity increases the chance of obtaining successful results from the more difficult samples submitted for analysis. Two of the new loci (D3S1358 and D19S433) are low molecular weight (between 100 and 150 base pairs); this improved the success rates of the degraded samples where high molecular weight loci may drop out. Of 26 non-primates tested, four gave results that appeared as single peaks and were unlikely to cause interpretation problems. None of the 19 micro-organisms tested gave discernible results. Extensive casework and simulated casework studies demonstrated that SGM and SGM plus results were comparable. There was one example of a null allele (primer binding site mutation) recorded at the HUMFIBRA locus (in both systems). However, a concordance study of 1000 samples using both SGM and SGM plus did not demonstrate any differences in typing.