Estimating Size of Drug Users in Macau: an Open Population Capture-Recapture Model with Data Augmentation Using Public Registration Data

Successful drug intervention policies rely on timely assessment of size of drug users and close monitoring of trend regarding drug abuse. Taking advantage of data collected by the Central Registration System for Drug Abusers of Macau (CRSDAM), this study applied open population capture-recapture models with data augmentation techniques to estimate the size of drug users and to identify influential factors on capture and survival probabilities from 2009 to 2014. In particular, the data augmentation technique was used to address missing data issues. The estimated size of drug users has been slowly declining from 2442 (95% Bayesian credible interval [BCI] 2042–2914) in 2009 to 807 (95% BCI 654–1000) in 2014 with a small fluctuation of 2251 (95% BIC 1950–2599) in 2011, and the estimated cumulative size of drug users is 6199 (95% BCI 5651–6873), which is correspondent to a prevalence rate of 1.20% of the current population aged 15 to 54. Although the estimated sizes of total, narcotic, and other drug users were declining, the size of stimulant users might be increasing. People who used narcotics as their first drug and who were reported by governmental agencies were more likely to stay in the registration system, while those who used needle injection were less likely to stay. Governmental agencies, higher education, and using needle injection were negatively associated with the probability of capture over time, while using narcotics as the first drug was positively associated with it.     

电阻测量法和光谱成像技术联用鉴别添改变造字迹

目的 黑色含碳笔形成的添改文件的检验一直是文件检验领域的难点和热点问题。对于原始字迹和添改字迹笔画均为黑色含碳色料书写的文件鉴定,通常借助光学仪器和显微设备进行形态学检验,易受外界环境和主体认知力的影响和限制。本文将通过笔画电阻测量法和光谱成像技术的联合应用,为鉴别黑色含碳笔添改字迹变造文件提供一种无损、便捷、有效的检验方法。方法 利用电阻测量仪和多波段光谱成像仪,选择同标准的测量点和基准点,分别对添改字迹与原始字迹笔画的电阻值和光谱数据进行测量、比较和分析。结果 实验结果显示不同黑色含碳笔书写的原始字迹和添改字迹笔画的电阻值和光谱数据存在差异,这种差异可以为鉴别添改字迹形成的变造文件提供依据。结论 电阻测量法和多光谱技术由于其无损、快速、准确等优点能够用于添改字迹的检验。两种技术并用的方法突破了含碳笔添加字迹鉴别中形态学检验的局限性,从定量的角度相互印证,使鉴定意见更为科学、可靠。