PubMed · 16478022
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Rodger Doyle. 2006. Sizing up.. https://doi.org/10.1038/scientificamerican0206-32
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The on-board distillation system (OBDS) was developed to extract, from gasoline, a high-volatility fuel for exclusive use during the starting and warm-up periods. The use of OBDS distillate fuel results in much improved mixture preparation, allowing combinations of air/fuel ratio and ignition timing that are not possible with gasoline, even with a fully warm engine. The volatility of the distillate is a function of the parent fuel volatility; however, the variability in distillate quality can be diminished via manipulation of the OBDS operating conditions. Thus, it is possible to develop aggressive starting calibrations that are relatively immune to variations in pump gasoline volatility. The key benefits provided bythe OBDS fuel relative to standard gasoline were found to be (1) improved mixture preparation allowing a 70% reduction of cranking fuel requirements, elimination of air-fuel mixture enrichment during the warm-up period, and significant extension of warm-up ignition timing retard; (2) a 57% decrease in catalyst light-off time, (3) emissions reductions over the FTP drive cycle of 81% for regulated hydrocarbons (NMOG); (4) emissions index (NMOG) approaching that of SULEV/PZEV vehicles; and (5) an apparent 1% increase in fuel economy over the FTP drive cycle.
Palynology is a long established and respected branch of environmental science that has been applied to criminal investigation in a meaningful way only in recent years. It has proved to be remarkably versatile in many kinds of criminal enquiry. It is not, however, an absolute science; palynological data are on a par with the suites of symptoms which allow medical practitioners to make diagnoses. Taphonomic variability is the main factor complicating interpretation of forensic palynological data. Palynological taphonomy may be defined as "all the factors that influence whether a palynomorph (pollen, spore, or other microscopic entity) will be found at a specific place at a specific time". If taphonomic variability is anticipated, and regularly tested, palynology will continue to keep its place in the armoury of useful forensic methods. Some assumptions made by palynologists engaged in palaeoecology and archaeology have been shown to be untenable in the forensic context. Palynological and botanical profiling of crime scenes has demonstrated anomalies which challenge received wisdoms. It has proved impossible to obtain palynological population data because every site is unique - expectations of any palynological profile can only be crude. The palynological status of any place must be tested every time. Without a body of analytical data from the actual crime scene, it is difficult to see how any palynologist can hope to present credible arguments under cross-examination. The statements made in this paper relate mainly to work carried out in the United Kingdom.