Estimating the uncertainty associated with Widmark's equation as commonly applied in forensic toxicology

No computation is performed more frequently by forensic toxicologists than that involving Widmark's equation. The equation is employed to estimate either the number of drinks consumed or the corresponding blood or breath alcohol concentration. Despite the wide use of Widmark's equation, rarely is an uncertainty estimate also provided. Estimates from Widmark's equation involve at least seven uncertain random variables. Uncertainty estimates are presented that rely on methods of general error propagation compared to a method developed by Widmark. Assuming reasonable variable and uncertainty estimates, the error propagation method yielded for N=10.4 drinks, a combined uncertainty (standard deviation) of 1.3 drinks (CV=12.3%). Similarly, estimating the blood alcohol concentration yielded for 0.120 g/100 ml, an uncertainty of 0.0255 g/100 ml (CV=21.2%). Widmark's uncertainty method yielded 1.6 drinks (CV=15.4%). The derivation of Widmark's uncertainty estimate is also presented, showing that he considered only rho and beta to be uncertain. Widmark estimates for the number of drinks should include a 2CV estimate of approximately 25% while the blood alcohol concentration estimate should include a 2CV estimate of approximately 42%. Including valid estimates of uncertainty should enhance the legal admissibility and confidence for Widmark estimations.     

Cognizance and Consultation of Randomized Controlled Trials among Ministerial Policy Analysts

Consultation of scientific evidence by policy actors has been the foci of attention of knowledge utilization scholars for decades. The present study questioned the extent to which randomized controlled trials (RCTs)—generally seen as the gold standard of scientific research—are known and consulted by policy analysts in ministerial settings. Using cross‐sectional data collected in 17 ministries in Québec (Canada), our study showed that fairly high levels of policy analysts report never having heard of RCTs, thus possibly hindering effective communication of scientific results to relevant policy makers. Statistical analyses reveal the importance of cognitive factors in explaining both phenomena.     

领导干部提拔模式对地方政府权力运行方向的影响

利用实证调查数据,通过交叉表分析,发现在提拔领导干部时,存在侧重考察"工作能力"与侧重考察"社会活动能力"两种模式,并且这两种模式对地方政府权力运行的集体决策的程度、为亲友用权、政府工作取向、决策偏好、政策执行取向有显著影响;通过探索性要素分析发现,领导干部提拔模式对政府权力运行方向的影响可以简化为"权力为整体利益服务"和"权力为小团体服务"两个方面;通过综合性结构方程模型分析验证了探索性分析的结论,表明领导干部选拔模式确实会对政府权力运行方向产生显著影响。同时发现:在提拔领导干部时,若强调后备人选的"能力和工作业绩"及"口碑",政府权力将更多地偏向于为公共利益服务;若"背景和关系"、"跑官买官"因素发生关键影响,政府权力则容易演变成为小团体牟利的工具。     

Rapid in situ repeatable analysis of drugs in powder form using reflectance near-infrared spectroscopy and multivariate calibration

This study takes the first step toward in situ analysis of powder drugs which does not require any alteration of the samples. A fast, inexpensive analytical method based on reflectance near-infrared (NIR) spectrometry and multivariate calibration was applied. A diode-array fiber-optic portable spectrometer in the 900-1700 nm range was employed. Samples were laboratory-prepared ternary powders (diacetylmorphine, caffeine, and paracetamol). Partial least squares regression was applied. The choice of the standard samples for calibration and validation was performed through a D-optimal experimental design. The explained variance was higher than 90%, and the relative root mean square errors were <2%. The number of principal components (6) was very low when compared with the number of raw variables (356 absorbance values). Response plots showed slopes and intercepts were very close to optimal values. Correlation coefficients ranged between 0.909 and 0.989. The method here proposed proved to be competitive with Fourier transform NIR spectrometry.     

The changes of fourier transform infrared spectrum in rat brain

Estimation of the time since death (postmortem interval [PMI]) is one of the most difficult problems in forensic investigations, and many methods currently are utilized to estimate the PMI. The goal of this study was to investigate the changes of attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectra of rat brain from postmortem time 0-144 h. The intensity ratios of major absorbance bands were examined (I(1066)/I(1392), I(1168)/I(1392), I(1234)/I(1454), I(1301)/I(1392), I(1647)/I(2956), I(2921)/I(2850), and I(1647)/I(1539)). The spectra of rat brain displayed prominent changes with increasing PMI. The band at 2871 and 1737 per cm became weak with the time increasing and even disappeared at postmortem 96 and 72 h, respectively. A close linear correlation was shown between the relative absorption intensity and the PMI, and the I(1234) /I(1454) offered a stronger correlation (r = 0.973). Our results indicate that ATR-FTIR spectroscopy may be a useful technique for estimating the PMI.     

A Stone’s Throw from the Metropolis: Re-Examining Small-Agency Homeland Security Practices

Police agencies nationwide have enhanced their homeland security preparedness capacity since the 9/11 attacks. Evidence suggests that departments have not uniformly adopted measures to prepare for and respond to critical incidents. Rather, larger agencies are more likely than their smaller peers to take such steps. Small agencies do not constitute a homogenous group; some experience geographic isolation while others are near major metropolitan areas. Unclear is whether small agencies (25 or fewer full-time sworn personnel), those that are commonly found to be less prepared, benefit from proximity to large-agency peers. This study examined whether physical and relational proximity to large departments contributed to homeland security preparedness in over 300 small departments. A structural equation model revealed that interactions with large agencies facilitated preparedness but physical proximity had no direct effect. Increasing geographic isolation from large-agency peers indirectly affected preparedness by stifling the level of inter-department interactions.     

New Approaches to Age Estimation Using Palatal Suture Fusion

Palatal suture fusion has seen little testing and/or application due in part to an inadequately described relationship to formal age ranges. This study presents a modified scoring method that examines fusion on samples of modern documented adult males and compares two Bayesian approaches to age estimation. In the first analysis, American and Portuguese collections were used to derive univariate and multivariate transition analysis (TA) parameters, which combined with an informative prior, estimated age in a sample of modern Americans and Portuguese. For the second analysis, a Bayesian multiple linear regression (BMLR) used indicator statuses as the independent variables with age as the dependent variable. Highest posterior density regions (HPDRs) and highest posterior density intervals (HDI) were calculated for a holdout sample. Final age estimates for the methods were tested for accuracy using cumulative binomial tests at 75% and 90% coverages. The HPDRs from multivariate TA captured age better for younger individuals, but consistently underaged. The cumulative binomial tests on the BMLR results indicated the prediction intervals performed as expected, and we show they are narrower (more precise) and/or more accurate than the corresponding HPDR. The modified method presented here formally links palatal suture obliteration to age using two different approaches, one of which (BMLR) is new to the aging literature. The BMLR provided results free from bias and more reasonable age ranges while maintaining accuracy. We present a look-up table and a free, simple R file for users to download and run their own estimates with BMLR.     

Situational factors and police use of force across micro-time intervals: A video systematic social observation and panel regression analysis

The current study analyzes police use of force as a series of time-bound transactions between officers, civilians, and bystanders. The research begins with a systematic social observation of use-of-force events recorded on police body-worn cameras in Newark, New Jersey. Researchers measure the occurrence and time stamps for numerous participant physical and verbal behaviors. Data are converted into a longitudinal panel format measuring all observed behaviors in 5-second intervals. Panel logistic regression models estimate the effect of each behavior on use of force in immediate and subsequent temporal periods. Findings indicate certain variables influence use of force at a distinct point in time, whereas others exert influence on use of force across multiple time periods. The most influential variables relate to authority maintenance theoretical constructs. This finding supports prior perspectives arguing that police use of force largely results from officer attempts to maintain constant authority over civilians during face-to-face encounters. Nonetheless, a range of additional variables reflecting procedural justice, civilian resistance, and bystander presence significantly affect when police use force during civilian encounters. Results provide nuance to theoretical frameworks considering use of force as resulting from the interplay between officer and civilian actions and reactions.     

Weight of authorship evidence with multiple categories of stylometric features: A multinomial-based discrete model

This study empirically demonstrates the efficacy of a two-level Dirichlet-multinomial statistical model (the Multinomial system) for computing likelihood ratios (LR) for linguistic, textual evidence with multiple stylometric feature types with discrete values. The LRs are calculated separately for each feature type, namely, word, character and part of speech N-grams (N = 1,2,3), which are combined as overall LRs through logistic regression fusion. The Multinomial system’s performance is compared with that of a previously proposed system with the cosine distance (the Cosine system) using the same data (i.e., documents collated from 2160 authors). The experimental results show that: (1) the Multinomial system outperforms the Cosine system with the fused feature types by a log-LR cost of ca. 0.01 ～ 0.05 bits; and (2) the Multinomial system is more advantageous in performance with longer documents than the Cosine system. Although the Cosine system is more robust overall against the sampling variability arising from the number of authors included in the reference and calibration databases, the Multinomial system can achieve reasonable stability in performance; for example, the standard deviation value of the log-LR cost becomes lower than 0.01 (10 random samplings of authors for the reference and calibration databases) with 60 or more authors in each database.     

大学生就业性别刻板印象的Logistic回归研究

以青岛3所高校的毕业生为研究对象进行样本抽取与问卷调研,对获得的264份有效问卷进行数据处理,通过因子分析得到刻板印象的5个构面：女性职业刻板印象、男性职业刻板印象、女性特质刻板印象、男性特质刻板印象与行为刻板印象。在此基础上运用Logistic回归分析的方法研究刻板印象与毕业生就业情况之间的关系的结果表明：女性职业刻板印象对毕业生就业情况有显著性负向影响,且毕业生在该构面的测量值上每增加1分,“毕业生签订就业协议比未签订就业协议”的概率将减少7．96％;男性特质刻板印象构面对毕业生就业情况有显著性正向影响,且毕业生在男性特质刻板印象的测量值上每增加1分,“毕业生签订就业协议比未签订就业协议”的概率将增加15．36％。