The Interplay between International Trade and Technological Change and the wage inequality in the OECD Countries

We estimate the impact of international trade and of trade-induced technological change on the wage inequality in the OECD countries, by estimating a two-stage mandated-wage regression. From our estimation we find no evidence on the Stolper-Samuelson effect of trade with the developing and newly industrialized countries. On the other hand, the evidenced technological change from technological competition did not have a strong effect on the increase of the wage differential between the different types of labour in the analyzed sample of OECD countries, which would have indicated that the bias of the technological change towards the skilled-intensive sectors is determined by trade in innovation-intensive goods.price competition, technological competition, wage inequality

Comparative Analysis of Word Embeddings for Capturing Word Similarities

Distributed language representation has become the most widely used technique for language representation in various natural language processing tasks. Most of the natural language processing models that are based on deep learning techniques use already pre-trained distributed word representations, commonly called word embeddings. Determining the most qualitative word embeddings is of crucial importance for such models. However, selecting the appropriate word embeddings is a perplexing task since the projected embedding space is not intuitive to humans. In this paper, we explore different approaches for creating distributed word representations. We perform an intrinsic evaluation of several state-of-the-art word embedding methods. Their performance on capturing word similarities is analysed with existing benchmark datasets for word pairs similarities. The research in this paper conducts a correlation analysis between ground truth word similarities and similarities obtained by different word embedding methods.Comment: Part of the 6th International Conference on Natural Language Processing (NATP 2020

Rapid qualitative and quantitative analysis of novel drug analogues via Desorption Electrospray Ionisation - Mass Spectrometry (DESI-MS)

University of Technology, Sydney. Faculty of Science.Desorption electrospray ionisation - mass spectrometry (DESI-MS) is an ambient ionisation technique that can be applied to the analysis of illicit drugs and novel drug analogues in seized drug material. Currently used preliminary identification techniques lack sensitivity and selectivity and are prone to false positive and false negative results. Therefore, it was important to investigate the use of DESI-MS as a novel preliminary identification technique in the analysis of a range of compounds with the potential for future automated library matching aiding in the rapid identification of unknowns. In this research, 4-methylmethcathinone (mephedrone or 4-MMC), cocaine, 1-benzylpiperazine (BZP), 3-trifuoromethylphenylpiperazine (TFMPP), 3-chlorophenylpiperazine (mCPP), 4-methoxyphenylpiperazine (MeOPP) and other amphetamine-type substances (ATS) such as amphetamine (AP), methylamphetamine (MA), 3,4-methylenedioxymethylamphetamine (MDMA), N,N-dimethylamphetamine (DMA), 4-methoxyamphetamine (PMA), and 4-methoxymethylamphetamine (PMMA) were the drugs of interest since they are increasingly prevalent drugs of abuse globally. The optimisation of the technique and the application of DESI-MS to the analysis of these compounds were demonstrated. A particularly suitable surface, semi-porous polytetra fluoroethylene (PTFE, Teflon) was utilised, as it gave superior signal stability and reproducibility as compared to other surfaces (polymethyl methacrylate (pMMA) and polyvinyl chloride (PVC)). The limits of detection (LOD) of 4-MMC and the piperazine analogues were determined to range between 0.0023 - 2.30 μg/mm². The LOD of the ATS was determined to be in the range 0.02 - 2.80 μg/mm². DESI-MS was also utilised in the preliminary analysis of illicit cocaine samples. The LOD of cocaine was determined to be 3.47 μg/mm². The chemical profiles obtained using DESI-MS were also compared to two current confirmatory analysis techniques, gas chromatography – mass spectrometry (GC-MS) and liquid chromatography – mass spectrometry (LC-MS). The by-products and impurities detected were used to link samples to their synthetic route of manufacture and to the precursors used. The detection of truxillines in the seized cocaine samples aided in determining their geographical origin. Selectivity and matrix effects were evaluated for the compounds of interest in each study. The effect of adulterants including caffeine, procaine, levamisole, lignocaine, paracetamol, and atropine on the detectability of cocaine were investigated. The detectability of ATS were evaluated by adding caffeine, paracetamol, magnesium stearate, and dimethyl sulfone. Piperazine compounds were adulterated using caffeine and a mixture of piperazines (TFMPP and BZP) was also evaluated since these are commonly found in combination. 4-MMC was adulterated with caffeine, paracetamol, MA, phentermine, AP, MDMA, 4-hydroxyamphetamine, 4-fluoroamphetamine, nordiazepam, diazepam, oxazepam, cocaine, heroin, methadone, cathine, cathinone, 4-diethylaminobenzaldehyde, 1-benzyl-3-pyrrolidinol, and methylone. In most cases, despite the presence of ion enhancement or suppression due to the addition of adulterant, the analytes remained detectable. Quantitative experiments for 2 μL spotted solutions of 4-MMC, using codeine-D₆ as an internal standard, introduced in the desorption spray solvent, showed a linear correlation (R² > 0.9840) over the range 50 – 800 μg/mL. The precision for triplicates analysed on five different days (n = 15) was <38 % RSD. The accuracy, expressed as relative error, was <13 %. Identification based on accurate mass and MS/MS spectra aided in discriminating compounds with the same molecular formula. The results obtained using DESI-MS demonstrate its applicability in the rapid qualitative analysis (and preliminary quantitative analysis of 4-MMC) of cocaine, 4-MMC, BZP, TFMPP, mCPP, MeOPP and ATS