Forensic analysis of bicomponent fibers using infrared chemical imaging

The application of infrared chemical imaging to the analysis of bicomponent fibers was evaluated. Eleven nominally bicomponent fibers were examined either side-on or in cross-section. In six of the 11 samples, infrared chemical imaging was able to spatially resolve two spectroscopically distinct regions when the fibers were examined side-on. As well as yielding characteristic infrared spectra of each component, the technique also provided images that clearly illustrated the side-by-side configuration of these components in the fiber. In one case it was possible to prepare and image a cross-section of the fiber, but in general the preparation of fiber cross-sections proved very difficult. In five of the 11 samples, the infrared spectra could be used to identify the overall chemical composition of the fibers, according to a published classification scheme, but the fiber components could not be spatially resolved. Difficulties that are inherent to conventional "single-point" infrared spectroscopy, such as interference fringing and sloping baselines, particularly when analyzing acrylic type fibers, were also encountered in the infrared chemical image analysis of bicomponent fibers. A number of infrared sampling techniques were investigated to overcome these problems, and recommendations for the best sampling technique are given. Chemical imaging results were compared with those obtained using conventional fiber microscopy techniques.     

Magnitude and durability of electoral change: Identifying critical elections in the U.S. Congress 1854–2010

The two hallmarks of a critical election and, hence, of a critical realignment are the magnitude of the observed change and the durability of that change. In addition to offering a new approach to measuring durable change in national party dominance, and providing a non-parametric criterion to identify unusual changes in seat/vote shares, we provide fresh insights via a unifying statistical approach that reflects both of these factors simultaneously. Furthermore, we assess the robustness of critical election determinations in two ways. First, we compare the magnitude of inter-election shifts with both average volatility over the entire time period and volatility relative to a particular time period. Second, as an alternative to the usual perspective, we consider critical elections not as a one-time cataclysm, but rather as a pair (or perhaps even triple) of consecutive substantial shifts, generated by the same underlying factors. Overall, we distinguish six elections that marginally or provisionally meet our criteria to be critical elections. But focusing on pairs of elections, 1858–60 and 1930–32 stand out as critical among all elections since the 1850s.