Gelatine lifting, a novel technique for the examination of indented writing

The limitations of the examination of indented writing impressions using electrostatic detection are often paper related. Paper types such as glossy paper, paper of high basis weight, and lithography or gravure-printed papers often give rise to problems resulting in a decrease in sensitivity or a lack of detection altogether. In this paper, a novel technique for the examination of indented writing is presented, which is in a sense complimentary to the technique of electrostatic detection as it is especially suitable for glossy-coated and printed paper types and can in some instances also deal with paper types of higher basis weight. Indented writing grooves will normally contain more particles than the surrounding nonindented areas due to damage of the surface layer resulting in a build-up of filler powder. The method presented uses black gelatine lifter slabs to lift the paper dust image off the surface of the paper. This image can quite easily be photographed using near-to-coaxial lighting. The gelatine lifting method outperforms oblique lighting for the detection of indented writing and is almost as sensitive as electrostatic detection if compared on the types of paper where both perform well. The main advantage of this new technique is, however, that it is especially suitable for those types of paper where electrostatic detection fails and is therefore a welcome addition to the range of methods available to a forensic document examiner for the examination of indented writing.     

Hearsay Versus Children's Testimony: Effects of Truthful and Deceptive Statements on Jurors’ Decisions

Researchers and courts are focusing increasing attention on the reliability of children's out-of-court statements, especially in relation to trials of child sexual abuse. The main goal of this study was to investigate the effects of presentation of children's out-of-court statements (e.g., hearsay) on jurors' perceptions of witness credibility and defendant guilt, and on jurors' abilities to reach the truth. Child participants experienced either a mock crime or were coached to say they experienced the crime when in fact they had not. During elaborate mock trials involving community member jurors, children's testimony was presented either: (1) live, (2) on videotape, or (3) via a social worker. Analyses revealed that testimony format directly influenced jurors' perceptions of child and social worker credibility (e.g., children were perceived as less likely to provide false statements if they testified live) as well as jurors' sympathy toward the child, all of which then predicted jurors' confidence in defendant guilt. Jurors had difficulty discerning accurate from deceptive child statements regardless of testimony format. Implications for psychology and the legal system are discussed.     

On The Application of Fuzzy Clustering for Crime Hot Spot Detection

   One of the fundamental challenges in crime mapping and analysis is pattern recognition. Efforts and methods to detect crime hot-spots, or geographic areas of elevated criminal activity, are wide ranging. For aggregate data, such as total crime events in a census tract(s), measures of spatial autocorrelation have proven useful. For disaggregate data (i.e. individual crime events), kernel density smoothing and non-hierarchical cluster analysis (e.g. k-means), are widely used. Non-hierarchical techniques are particularly effective in delineating geographic space into areas of higher or lower crime concentrations, because each observation is assigned to one and only one cluster. The resulting set of partitions provides clear-cut spatial boundaries that can be used for hot-spot evaluation and interpretation. However, the strength of non-hierarchical methods can also be viewed as a weakness. Although the hard-clustering of observations into a set of discrete clusters is helpful, there are many cases where ambiguity exists in the data. In such cases, a more generalized approach for hot-spot detection would be helpful. The purpose of this paper is to explore the use of a generalized partitioning method known as fuzzy clustering for hot-spot detection. Functional and visual comparisons of fuzzy clustering and two hard-clustering approaches (medoid and k-means), across a range of cluster values are analyzed. The empirical results suggest that a fuzzy clustering approach is better equipped to handle intermediate cases and spatial outliers.

Will the Truth Come Out? The Effect of Deception,Age, Status,Coaching, and Social Skills on CBCA Scores

The impact of Veracity, Age, Status (witness or suspect), Coaching (informed or uninformed regarding CBCA), and Social Skills (social anxiety, social adroitness, and self-monitoring) on Criteria-Based Content Analysis scores was examined. Participants (aged 5–6, 10–11, 14–15, and undergraduates) participated in a rubbing the blackboard event. In a subsequent interview they told the truth or lied about the event. They were accused of having rubbed the blackboard themselves (suspect condition) or were thought to have witnessed the event (witness condition), and were or were not taught some CBCA criteria prior to the interview. CBCA scores discriminated between liars and truth tellers in children, adults, witnesses, and suspects. However, truth tellers obtained higher CBCA scores than liars only when the liars were uninformed about CBCA. CBCA scores were correlated with social skills. It is argued that these findings should caution those who believe that the validity of CBCA has been conclusively demonstrated.     

“He's guilty!”: Investigator Bias in Judgments of Truth and Deception

Detecting deception is an inherently difficult task, but one that plays a critical role for law enforcement investigators in the interrogation room. In general, research has failed to indicate that performance in this domain is improved by training or prior experience. A signal detection framework is applied to the paradigm to better conceptualize the influence of these two factors. We found that although neither factor influenced discrimination accuracy, there was an effect on response bias such that training and prior experience appeared to increase the likelihood of responding deceit as opposed to truth. This investigator bias was observed both in a review of the literature and in this study of North American law enforcement investigators who took part in a forensically based deception-detection task. Possible theoretical mechanisms and practical implications of these findings are discussed.     

Do Juries Meet Our Expectations?

Surveys of public opinion indicate that people have high expectations for juries. When it comes to serious crimes, most people want errors of convicting the innocent (false positives) or acquitting the guilty (false negatives) to fall well below 10%. Using expected utility theory, Bayes' Theorem, signal detection theory, and empirical evidence from detection studies of medical decision making, eyewitness testimony, and weather forecasting, we argue that the frequency of mistakes probably far exceeds these tolerable levels. We are not arguing against the use of juries. Rather, we point out that a closer look at jury decisions reveals a serious gap between what we expect from juries and what probably occurs. When deciding issues of guilt and/or punishing convicted criminals, we as a society should recognize and acknowledge the abundance of error.     

应用Dot-ELISA检测牛胴体沙门菌

应用Dot ELISA法对西宁市某屠宰点 71份牛胴体淋巴结进行了沙门菌检测 ,同时与常规分离培养鉴定技术比较。结果 ,在 71份牛胴体样本中 ,用Dot ELISA法检出沙门菌阳性 33份 ,阳性率为 4 6 .4 8% (33/71) ;而用常规分离培养鉴定技术检出沙门菌阳性 31份 ,阳性率为 4 3.6 6 %(31/71) ;2种方法的阳性符合率为 81.82 % ,阳性检出率差异不显著 (P >0 .0 5 )。     

产蛋下降综合征病毒PCR检测方法的建立

根据已报道的腺病毒DNA序列 ,设计合成了 1对核苷酸引物 ,引物间隔约 63 0bp。用该引物对EDS76病毒内蒙古分离株 (N3 ,N4 )和参考株 (AV 1 2 7)核酸进行聚合酶链式反应 (PCR)。结果 ,均扩增出了约 63 0bp的特异性DNA片段。所建立的PCR方法可检出 1 0 0pg的样品模板。结果表明 ,此PCR方法是检测EDS76病毒的一种简便快速、特异性强和灵敏度高的方法     

鹅细小病毒强毒PCR检测方法的建立

参照GenBank中登录的鹅细小病毒 (GPV)B株的全基因序列 ,针对GPV的VP3保守基因设计了 1对引物 ,建立了GPV的PCR检测方法。采用该方法检测GPV能够扩增出预期大小约 4 41bp的特异性片段 ,而对鸭瘟病毒 (DPV)、鹅源致病性大肠埃希氏菌 (E .coli)O8和O1、雏鹅新型病毒性肠炎病毒 (NGVEV)呈阴性反应。该法检测GPV核酸的灵敏度可达 0 .4 7pg ;对GPV强毒皮下注射感染雏鹅各器官的检测结果表明 ,感染后 8h即可从心、肝病料中检出病毒DNA ,感染后 2 4h可从延髓、胸腺、胰腺、十二指肠、空肠、盲肠、腔上囊、心、肝、脾、肺、肾、血液、小脑、直肠、肌肉、粪便中检出GPVDNA ,感染 4 8h后可从骨髓中检出病毒DNA ,感染 312h后仍能从十二指肠、空肠、盲肠、心、肝、肾、粪便中检出病毒DNA。病毒分离阳性的可疑病料PCR检测为阳性 ,对临床送检病料的检测结果表明 ,PCR的敏感性显著高于病毒分离。     

断奶猪多系统衰弱综合征血清抗体检测

从北京、河北、山东、天津、江西、吉林、河南7省(市)22个猪群采集各类猪血清样品559份,用猪圆环病毒Ⅱ型(PCVⅡ)克隆化特异性表达抗原包被反应板,采用ELISA检测断奶猪多系统衰弱综合征(PMWS)抗体.结果,20日龄未断奶仔猪阳性率为0(0/58)、1～2月龄断奶仔猪阳性率为16.5%(23/139),后备母猪阳性率为43.3%(61/141),经产母猪阳性率为85.6%(107/125),肥猪阳性率为51.0%(49/96),559头猪总阳性率为42.9%(240/559).检测临床有疑似PMWS症状的4～5月龄生长肥育猪6头,结果均为阳性;检测临床有疑似PMWS症状的1～2月龄仔猪9头,结果均为阴性.