三七中人参炔醇的提取、分离和鉴定

目的:提取、分离和鉴定三七中人参炔醇.方法:采用超临界CO2萃取三七脂溶性成分,硅胶柱层析、制备薄层分离,并通过波谱技术(UV、IR、MS、1HNMR、13CNMR)分析鉴定人参炔醇化学结构.结果:从三七中分离并鉴定了人参炔醇成分,得率为0.077%.结论:应用超临界CO2萃取三七中脂溶性成分并分离其中的人参炔醇,得率较高.     

Quantitative evaluation of latent fingermarks with novel enhancement and illumination

A variety of suspended silica and metal nanoparticles have been used over the last 20 years to enhance latent fingermarks. This study quantitatively evaluates enhancement of natural and sebum-enriched fingermarks from three adult subjects acquired with a consistent applied force on glass with a fingermark press using suspended commercially available polystyrene (PS) particles. Images of the enhanced fingermarks acquired with total internal reflection (TIR), or standard overhead white light (WL), illumination are compared with fingermarks enhanced with conventional methods including cyanoacrylate fuming. The different enhancement and illumination methods are quantified based on the brightness and contrast of the fingermark images, as well as the number of minutiae that can be identified and matched to those on an inked manually acquired “template” fingermark using automatic fingerprint identification system (AFIS) software. Enhanced fingermarks acquired with the press are shown to be more consistent than manually acquired fingermarks based on these metrics. The results demonstrate that TIR illumination from a large-area illuminator built in house gives enhanced fingermark images with more matched minutiae and contrast superior to that for WL illumination for all types of enhancement. “Wet-powdering” with PS particles gives fingermark images that are for the most part comparable in terms of the number of matched minutiae to fingermarks enhanced with more conventional methods, suggesting that this novel enhancement method has a performance comparable to conventional enhancement methods. Interestingly, the age of the fingermark appears to have almost no effect on this new type of enhancement; sebum-enriched fingermarks ranging in age from 12 h to 435 days appear to have statistically identical numbers of matched minutiae.     

Performance of forensic facial comparison by morphological analysis across optimal and suboptimal CCTV settings

Facial comparison is an important yet understudied discipline in forensics. The recommended method for facial comparison in a forensic setting involves morphological analysis (MA) with the use of a facial feature list. The performance of this approach has not been tested across various closed-circuit television (CCTV) conditions. This is of particular concern as video and image data available to law enforcement is often varied and of subpar conditions. The present study aimed at testing MA across two types of CCTV data, representing ideal and less than ideal settings, also assessing which particular shortcomings arose from less-than-ideal settings. The study was conducted on a subset of the Wits Face Database arranged in a total of 225 face pools. Each face pool consisted of a target image obtained from either a high-definition digital CCTV camera or a low-definition analogue CCTV camera in monochrome, contrasted to 10 possible matches. The face pools were analysed and scored using MA and confusion matrices were used to analyse the outcomes. A notably high chance corrected accuracy (CCA) (97.3%) and reliability (0.969) was identified across the digital CCTV sample, while in the analogue CCTV sample MA appeared to underperform both in accuracy (CCA: 33.1%) and reliability (0.529). The majority of the errors in scoring resulted in false negatives in the analogue sample (75.2%), while across both CCTV conditions false positives were low (digital: 0.3%; analogue: 1.2%). Even though hit rates appeared deceptively high in the analogue sample, the various measures of performance used and particularly the chance corrected accuracy highlighted its shortfalls. Overall, CCTV recording quality appears closely associated to MA performance, despite the favourable error rates when using the Facial Identification Scientific Working Group feature list.     

Presentation of acoustic characteristics with network models for dialect identification

Objective To explore the presentation of acoustic characteristics with network models for dialect identification so as to screen out the optimal singular model for automatic dialect classifier. Methods Four selected typical neural network models for acoustic feature extraction, SOM (self-organizing feature Map), RNN (recurrent neural network), LSTM (long short-term memory network) and CNN (convolutional neural network), were individually simulated through python. With the dataset containing typical dialects (6036 samples of 105 persons’ spoken voices) from 13 cities in Jiangsu province, three aggregates were respectively built up for purpose of training, verification and test at the division ratio of 6:2:2. The test aggregate was then edited into sub-aggregates of 3 and 10 seconds, having each further added of white noise to form the sub-aggregates owning signal-to-noise ratio (SNR) of 3 and 10 dB. Thus, 4 test aggregates were thereby produced, with each containing 1207 samples. The appropriate classifiers were chosen to evaluate the performance of four above-selected models into their operations of training, verification and test. For the dialect identification, every selected network model was verified of its ability to extract features from the test aggregates owning different SNR and duration. Results With the previously-normalized data and network parameters, the confusion matrices of models were obtained from the output data of 4 neural network models processing into 4 test aggregates, having resulted in the Macro-F1 and Micro-F1 scores that are useful and eligible for evaluation of multi-classification problem. The results showed that LSTM and CNN are significantly better of performance than SOM and RNN. SOM is obviously more sensitive to the SNR of test samples, though having poor identification accuracy with the 3dB test aggregate. RNN has the improved accuracy for dialect identification, yet having the insufficient representation ability to key information of long-term samples. LSTM achieves the optimal evaluation scores of 93.1% (Macro-F1)/92.7% (Micro-F1) with 10dB/10s test aggregate, excelling in overcoming the bug of RNN with its characteristic structural unit. CNN is stable of identification accuracy, not easily affected with the length of speech fragments, thereby having better performance in noise-resistibility for substandard recordings. Owning the nonlinear transformation operations of convolution and pooling, CNN model is of good nonlinear expression ability to demonstrate nice fitting performance for information representation in dialect classification although it is incompetent in real-time presentation with the identified material. Conclusions LSTM+CNN framework is of better acoustic characteristics performance and robustness, capable of meeting the further updating development and application of automatic dialect identification. Besides, the audio sample duration and SNR are still the key for a model (singular or coalesced from two or more) to improve its identification accuracy. © 2021, Editorial Office of Forensic Science and Technology. All rights reserved.     

Effect of Head Position on Facial Soft Tissue Depth Measurements Obtained Using Computed Tomography

Facial soft tissue depth (FSTD) studies employing clinical computed tomography (CT) data frequently rely on depth measurements from raw 2D orthoslices. However, the position of each patient's head was not standardized in this method, potentially decreasing measurement reliability and accuracy. This study measured FSTDs along the original orthoslice plane and compared these measurements to those standardized by the Frankfurt horizontal (FH). Subadult cranial CT scans (n = 115) were used to measure FSTDs at 18 landmarks. Significant differences were observed between the methods at eight of these landmarks (p < 0.05), demonstrating that high‐quality data are not generated simply by employing modern imaging modalities such as CT. Proper technique is crucial to useful results, and maintaining control over head position during FSTD data collection is important. This is easily and most readily achieved in CT techniques by rotating the head to the FH plane after constructing a 3D rendering of the data.     

Skeletal Indicators of Stress: A Component of the Biocultural Profile of Undocumented Migrants in Southern Arizona,

The ability of forensic anthropologists in the United States to distinguish the remains of foreign nationals from those of American citizens may be crucial to the identification process. This study adds new criteria for identifying Hispanic foreign nationals in southern Arizona to those previously outlined by Birkby et al. (J Forensic Sci 53, 2008, 29) in the “cultural profile.” Skeletal indicators of nonspecific stress were evaluated in undocumented border crossers (UBCs) at the Pima County Office of the Medical Examiner and in documented American samples. Odds ratios show significant associations between UBC status and the presence of porotic hyperostosis and enamel hypoplasias, which are, respectively, 7.9 and 3 times more prevalent among UBCs. These findings are consistent with disparities in access to adequate nutrition and health care during childhood. In conjunction with context and other biocultural factors, the presence of these conditions should prompt practitioners to consider that unidentified remains may represent foreign nationals.     

Healed Depressed Parasagittal Skull Fractures—A Feature of Archaic Australian Aboriginal Remains

The skeletal remains of eight Australian Aboriginals with healed depressed skull fractures were examined. Male:female ratio 5:3; age range 20‐60 yrs. Burial dates by ¹⁴C dating in three cases were 500 years BP (n = 2) and 1300 BP. There were 13 healed depressed skull fractures manifested by shallow indentations of cortical bone and thinning of diploe, with no significant disturbance of the inner skull tables. Nine (69%) were located within 35 mm of the sagittal suture/midline. These lesions represent another acquired feature that might be helpful in suggesting that a skull is from a tribal Aboriginal individual and may be particularly useful if the remains are represented by only fragments of calvarium. While obviously not a finding specific to this population, these healed injuries would be consistent with the possible results of certain types of conflict behavior reported in traditional Aboriginal groups that involved formalized inflicted blunt head trauma.     

Quantification of Osteon Morphology Using Geometric Histomorphometrics

Many histological methods in forensic anthropology utilize combinations of traditional histomorphometric parameters which may not accurately describe the morphology of microstructural features. Here, we report the novel application of a geometric morphometric method suitable when considering structures without anatomically homologous landmarks for the quantification of complete secondary osteon size and morphology. The method is tested for its suitability in the measurement of intact secondary osteons using osteons digitized from transverse femoral diaphyseal sections prepared from two human individuals. The results of methodological testing demonstrate the efficacy of the technique when applied to intact secondary osteons. In providing accurate characterization of micromorphology within the robust mathematical framework of geometric morphometrics, this method may surpass traditional histomorphometric variables currently employed in forensic research and practice. A preliminary study of the intersectional histomorphometric variation within the femoral diaphysis is made using this geometric histomorphometric method to demonstrate its potential.     

Who are the Unclaimed Dead?

Unclaimed dead are deceased persons with no known next of kin (NoK) or NoK was located but did not claim the deceased. Unclaimed dead in Marion County, Indiana, 2004–2011, are examined. Comparisons are provided of the unclaimed to the claimed dead population and county death patterns. Race, gender, marital status, age, location, manner and cause of death, NoK, and days to disposition are analyzed. The unclaimed dead were disproportionately male, slightly more likely to be Black, younger at death, died from natural causes, had unknown marital status, were equally likely as not to have NoK, did not die in a hospital, and were subject to autopsy. Nearly half the unclaimed had NoK who did not claim the body; the other half had no identifiable NoK. Unclaimed were more likely to have an autopsy and to die from external causes. Most unclaimed were identified by means outside fingerprints or DNA.     

Fingerprint Ridge Density as a Potential Forensic Anthropological Tool for Sex Identification

In cases of partial or poor print recovery and lack of database/suspect print, fingerprint evidence is generally neglected. In light of such constraints, this study was designed to examine whether ridge density can aid in narrowing down the investigation for sex identification. The study was conducted on the right‐hand index digit of 245 males and 246 females belonging to the Punjabis of Delhi region. Five ridge density count areas, namely upper radial, radial, ulnar, upper ulnar, and proximal, were selected and designated. Probability of sex origin was calculated, and stepwise discriminant function analysis was performed to determine the discriminating ability of the selected areas. Females were observed with a significantly higher ridge density than males in all the five areas. Discriminant function analysis and logistic regression exhibited 96.8% and 97.4% accuracy, respectively, in sex identification. Hence, fingerprint ridge density is a potential tool for sex identification, even from partial prints.