Evaluation of Raman spectroscopy for the analysis of colored fibers: a collaborative study

A collaborative study on Raman spectroscopy was carried out by members of the ENFSI (European Network of Forensic Science Institutes) European Fibres Group (EFG) on three dyed fibers: two red acrylics and one red wool. Raman instruments from six different manufacturers were tested as well as nine different laser wavelengths ranging from blue (lambda = 458 nm) to near infrared-NIR (lambda = 1064 nm). This represents the largest comparison study of Raman analytical parameters carried out on identical fiber samples. For the chosen fiber and dye samples, red lasers (lambda = 633 and 685 nm) gave the poorest spectral quality whereas blue (458 nm), green (514 nm) and near infrared lasers (785, 830 and 1064 nm) provided average results. Blue (488 nm) and green lasers (532 nm) globally gave the best quality spectra. Fluorescence problems were often encountered with some of the excitation wavelengths and therefore a flexible Raman instrument equipped with different lasers can be recommended to measure forensic fiber samples. The instrument should also be equipped with a Raman microscope in order to be able to focus on a single fiber. This study shows that Raman spectroscopy usually enables the identification of the main dye present in a colored fiber; however, minor dye components are much more difficult to detect. SERRS (Surface Enhanced Resonance Raman Scattering) techniques give an improvement of the dye's spectral intensity but no spectral improvement was observed for the two red acrylic and red wool fibers tested.     

Ego development in adolescence: Longitudinal studies

Adolescents from four schools (one inner-city, two suburban, and one private) were tested two or three times using the Washington University Sentence Completion Test of Ego Development. Testing intervals ranged from 1.5 to 6 years. About half (N=193) the original pool was retested at twelfth grade. Every sample showed a mean rise in ego level; for six of eight samples that rise was statistically significant. Every pair of testings showed a postive correlation between scores; 10 of 14 correlations were significantly different from zero. Thus both test-retest correlations (about 0.5) and change scores support the hypothesized sequence of ego development. Significant correlation between ego level and intelligence occurred in two schools (0.6 at elementary and junior high grades and 0.4 at twelfth grade), but correlation was about zero in the private school.These studies were supported by Grant MH-05115 and Research Scientist Award MH-00657, both from the National Institute of Mental Health, Public Health Service.Received her Ph.D. from Washington University. Main interest is adolescent development.Received her Ph.D. from the University of California, Berkeley. Main interest is theory and measurement of ego development.