A GC/MS study of the drying of ballpoint pen ink on paper

The determination of the age of an ink entry from a questioned document is often an essential problem and a controversial issue in forensic sciences. Therefore, it is important to understand the aging process of the different components found in ink. The aim of this work was to study the drying process of ballpoint ink, characterised by the disappearance of volatile solvents from the ink entry. Phenoxyethanol is of particularly high interest as it is found in more than 80% of the blue ballpoint pens at different concentrations. Liquid extraction followed by splitless gas chromatography/mass spectrometry in the selected ion mode was used to measure the quantitative decrease of solvents from ink entries made with a blue Parker ballpoint pen. Quantities of ethoxyethoxyethanol, dipropylene glycol, phenoxyethanol and phenoxyethoxyethanol were studied in ink entries up to 1.5 years old, thus allowing to calculate aging curves for this particular pen. The low quantities of solvents (in the microgram range for a 1 cm ballpoint entry) were found to decrease quickly after deposition of the ink on paper through the competitive processes of evaporation and diffusion. Losses of up to 75% of solvents were observed after a few seconds. The amount of ethoxyethanol stopped decreasing after about 10 days (quantities reached the nanogram range for a 1 cm ballpoint entry), while the aging curves of dipropylene glycol, phenoxyethanol and phenoxyethoxyethanol level off considerably after 2 weeks. It was observed that ethoxyethanol, dipropylene glycol and phenoxyethanol can also migrate from one sheet of paper to another if placed close enough (e.g. in a book or a stack of papers), therefore contamination from fresh ink strokes from other paper sheets has to be taken into account for those solvents. In this paper we demonstrate that differentiation between fresh ink (<2 weeks) and older inks is possible under laboratory storage conditions. For real cases samples, more parameters have to be studied and other possible pathways have to be considered.     

LC-MS/MS analysis of fentanyl and norfentanyl in a fatality due to application of multiple Durogesic transdermal therapeutic systems

Fentanyl is a potent synthetic narcotic analgesic administered in the form of a transdermal patch for the management of chronic pain. A 78-year-old woman with a history of cancer was found dead in bed. She was lying on her back. The external examination revealed 10 Durogesic transdermal therapeutic systems (100 microg/h fentanyl) on the body. Liquid-liquid extraction and liquid chromatography tandem mass spectrometry with electrospray source in positive ionization mode was applied for the quantitation of fentanyl and its major metabolite norfentanyl in the post-mortem samples. Fentanyl-d5 and norfentanyl-d5 were used as internal standards. Multiple reaction monitoring was used for specific detection. Calibration was performed by addition of standard solutions to drug-free matrix (blood, urine and liver) prior to extraction. The method showed good linearity for fentanyl and norfentanyl over a concentration range of 5-150 microg/L in reconstituted extracts with coefficients of determination equal or greater than 0.998. Percent mean within-day precision and accuracy of 0.9-1.0% and 99.4-101.1% for fentanyl and 2.0-4.5% and 93.1-101.0% for norfentanyl were obtained. Mean extraction recoveries varied between 95.5% and 100.3% for fentanyl and 39.2-57.4% for norfentanyl. The following fentanyl (norfentanyl) concentration in the post-mortem samples were measured; 28.6 microg/L (3.0 microg/L) in right and 28.2 microg/L (3.5 microg/L) in left subclavian blood, 21.3 microg/L (<2 microg/L) in right and 20.9 microg/L (<2 microg/L) in left femoral blood, 37.6 microg/L (4.2 microg/L) in right and 33.9 microg/L (4.4 microg/L) in left ventricular blood, 282.9 microg/L (121.2 microg/L) in urine, 688.2 microg/L in stomach contents, 122.5 microg/L (25.4 microg/L) in bile, 19.5 microg/L (< 2 microg/L) in vitreous humour, 203.0 microg/kg (26.6 microg/kg) in liver and 78.6 microg/kg (46.3 microg/kg) in kidney. We concluded that the woman's death was caused by acute intoxication with fentanyl. The manner of death was presumed to be suicide due to excessive administered Durogesic transdermal therapeutic systems.     

Efficient Estimation of Time-Invariant and Rarely Changing Variables in Finite Sample Panel Analyses with Unit Fixed Effects

e-mail: tpluem{at}essex.ac.uk (corresponding author) This paper suggests a three-stage procedure for the estimationof time-invariant and rarely changing variables in panel datamodels with unit effects. The first stage of the proposed estimatorruns a fixed-effects model to obtain the unit effects, the secondstage breaks down the unit effects into a part explained bythe time-invariant and/or rarely changing variables and an errorterm, and the third stage reestimates the first stage by pooledOLS (with or without autocorrelation correction and with orwithout panel-corrected SEs) including the time-invariant variablesplus the error term of stage 2, which then accounts for theunexplained part of the unit effects. We use Monte Carlo simulationsto compare the finite sample properties of our estimator tothe finite sample properties of competing estimators. In doingso, we demonstrate that our proposed technique provides themost reliable estimates under a wide variety of specificationscommon to real world data. Authors' note: Earlier versions of this paper have been presentedat the 21st Polmeth Conference at Stanford University, PaloAlto, July 29–31, 2004, the 2005 MPSA Conference in Chicago,April 7–10, and the APSA Annual Conference 2005 in Washington,September 1–4 2005. We thank the referees of PoliticalAnalysis and Neal Beck, Greg Wawro, Donald Green, Jay Goodliffe,Rodrigo Alfaro, Rob Franzese, Jörg Breitung, and PatrickBrandt for helpful comments on previous drafts. Any remainingdeficiencies are our responsibility.     

Fear of Floating and the External Effects of Currency Unions

The introduction of the Euro has considerably affected the de facto monetary policy autonomy—defined as independence from monetary policy in the key currency areas—in countries outside the European Currency Union (ECU). Using a standard open economy framework, we argue that de facto monetary policy autonomy has significantly declined for countries that dominantly trade with the ECU and slightly increased for countries that dominantly trade with the Dollar zone. The predictions of our model find support in the data. We estimate the influence of the Bundesbank's/ECB's and the Fed's monetary policies on various country groups. The de facto monetary policy autonomy of both non-Euro EU members and EFTA countries declined with the introduction of the Euro. This effect was slightly stronger for the EU member countries than for EFTA countries as our theory predicts. At the same time, the de facto monetary policy autonomy of Australia and New Zealand vis-à-vis the US Dollar has (moderately) increased.     

Combination of Face Regions in Forensic Scenarios

This article presents an experimental analysis of the combination of different regions of the human face on various forensic scenarios to generate scientific knowledge useful for the forensic experts. Three scenarios of interest at different distances are considered comparing mugshot and CCTV face images using MORPH and SC face databases. One of the main findings is that inner facial regions combine better in mugshot and close CCTV scenarios and outer facial regions combine better in far CCTV scenarios. This means, that depending of the acquisition distance, the discriminative power of the facial regions change, having in some cases better performance than the full face. This effect can be exploited by considering the fusion of facial regions which results in a very significant improvement of the discriminative performance compared to just using the full face.     

To P or not to P? The Usefulness of P‐values in Quantitative Political Science Research

This contribution gives a short overview over the mechanics of significance testing in inferential statistics, in particular linear models, and tries to put the discussion about the usefulness of p‐values into a broader perspective of scientific practise. This discussion needs to be embedded into the larger debate about the credibility crises faced by empirical social science research. In particular, it seems of utmost importance to discuss what the profession as a whole, journals, publishers, as well as editors can do to encourage better research practise that generates reliable and useful empirical findings.