9种介质上滴落状血迹的模拟实验研究和应用

目的观察不同高度和速度滴落在9种介质上的血迹的形态、大小及与高度,速度之间的关系。方法采用抗凝人血,在静态和动态条件下,进行滴落状血迹的模拟实验,观察血迹的形态,测量其直径,用spss12.0统计软件进行分析。结果在静态条件下,滴落血迹,多呈圆形,其周围有毛刺状突起;7种介质上滴落血迹的大小(直径)与滴落高度之间有较好的线性关系,可得出回归方程。在慢走、急走、跑、快跑动态条件下,滴落血迹为圆形或椭圆形,沿运动方向的一侧出现突起;高度、速度分别对血迹形态有影响,在水泥路面上两者有交互作用。结论滴落状血迹形态和大小,可用于对出血部位的高度、运动速度和方向的推断。     

动脉喷溅血迹动力学及形态学的模拟实验观察

目的观察不同压力、管径对在水平方向上形成的喷溅状血迹的喷射距离及形态的影响。方法建立室内现场环境,利用自制的模拟喷射装置,在60～210mmHg范围内设6种压力,在1.5～4.5mm范围内设4种管径条件,于50、100、150cm 3种高度,制作动脉喷溅血迹。观察水平面上不同喷射高度的喷溅血迹的分布范围、血迹大小及形态特征,并测量其距离,采用SPSS 13.0统计软件进分析,并进行方差检验。结果在不同高度,血液喷射距离随压力增大而增加,随管径增大而减小,两因素间存在交互作用,距离与压力及管径存在较好的线性关系,可得出回归方程。而喷溅血迹的形态特征总体趋势为:高度越高圆形血滴直径约大;管径越粗,边缘毛刺状突起越明显;压力越大,喷射距离越远,且卫星状血迹逐渐增多,拖尾更拉长;随管径的增加,出现椭圆形血滴所需的压力越高。结论动脉喷溅血迹的形态及喷射距离的观察与测量,可用于推断命案现场喷溅源位置及人体受损伤时的体位。     

二次溅落状血迹形态的模拟实验观察

目的观察二次溅落状血迹的形态特征,探讨其形成机理及与行为方式的关系。方法建立室内现场环境,用10mL血液,以单滴连续滴落或一次性倾倒方式,从10～160 cm高度以10 cm为间隔,制作二次溅落状血迹模型;用棍棒打击及撞击方式制作低位打击及头部撞击溅落血迹模型。观察各种血迹分布,并分析比较其形态差异。结果二次溅落状血迹和头部撞击溅落状血迹在垂直面上均形成倒三角形空白区域的分布形态,但前者分布面积较后者小;低位打击溅落在垂直面上的血迹无此特征,且打击飞溅血滴的飞行角度大于二次溅落血迹。结论利用二次溅落状血迹的形态特征,对于鉴别低位溅血、分析行为方式、证实相关证词具有重要价值。     

水泥地面上滴落状血迹形态的模拟实验

目的观察水泥地面上不同高度、速度对滴落状血迹的形态和大小,应用于现场勘验。方法采用等量抗凝人血,在静态和动态条件下,进行滴落状血迹的模拟实验,观察血迹的形态,测量其直径,用专业统计软件进行分析。结果在静态条件下,滴落状血迹呈圆形,其周围有毛刺状突起;滴落状血迹的大小(直径)与滴落高度之间有较好的线性关系,可得出回归方程。在慢走、急走、跑、快跑动态条件下,滴落状血迹为圆形或椭圆形,沿运动方向的一侧出现突起;高度、速度分别对血迹形态有影响,而且两者有交互作用。结论滴落状血迹形态和大小的观察和测量,可用推断出血部位的高度、运动速度和方向。     

中空性皮下出血宽度与致伤木棒直径的相关性

目的观察不同直径和不同打击力度的圆柱形木棒对垂直方向打击皮肤所形成的中空性皮下出血形态的相关性。方法采用生物力学击打装置,使用5种不同直径（2.0～4.0cm）木棒,从零递增击打力度（0～2300N）,对活体乳猪背部皮肤进行打击,观察乳猪背部皮肤中空性皮下出血分布范围、色泽及形态特征,并采用SPSS 13．0统计软件对所得数据进行分析。结果中空性皮下出血出现的最小打击力度阈值（230N）,随打击工具直径的增大而阈值增大（230～810N）;同一直径的木棒在不同击打力度下所形成的中空性皮下出血总宽度及中空宽度均没有统计学差异（P〉0.05）。中空性皮下出血的范围随木棒直径的增大而增大（R2=0．953,P〈0．01）;皮下出血总宽度及中空宽度与打击物直径,存在较好的正相关性（R2=0．797,P〈0．01）,符合一元线性回归方程模型。结论本研究可望用于推断垂直打击造成中空性皮下出血的木棒直径的大小,为钝器致伤工具的判断提供初步的理论依据。     

现场血迹推断出血点位置的研究进展

血迹是命案现场最常见的痕迹之一,对血迹形态的分析是一种重建犯罪现场的有效方法,而根据现场血迹推断出血点位置则是血迹形态分析的主要任务之一。随着血迹研究的不断发展,出现了许多不同的方法（如传统拉线法、三角函数法、绘图法、计算机程序法、公式计算法、回归方程法等）用于推断出血点位置。通过结合国内外相关文献,对不同的方法进行了综述,以期为相关研究提供参考。     

浅谈血迹分类

近年来，命案现场上血迹（bloodstain）的分析已越来越受法医工作者的重视。但是，复习国内外的教材和文献资料，发现存在血迹分类较为笼统、某些概念尚不明晰的问题，比如：将器械作用于有血处所引起的血迹和挥动沾血的器械所产生的血迹一并称之为喷溅状血迹，血掌指印及血足迹缺乏明确的归类等等。所以，实有必要对血迹的分类及其基本概念重新进行审视。为此，笔者斗胆将血迹的分类进行归纳，抛砖引玉，与同行们共同探讨。根据血迹形成的机制不同，结合血迹的形态特点，笔者以为可将血迹分成１０种类型。１喷溅状血迹喷溅状血迹（projecte…     

垂直抛甩状血迹形态的模拟观察

目的观察不同类型打击工具的垂直抛甩状血迹形态。方法选择常见的菜刀、匕首、方锤、铁管作为打击工具。用沾新鲜鸡血5 m L的工具自上而下进行垂直抛甩,对距离垂直墙壁30 cm处形成的血迹形态进行测量分析,通过对抛甩血迹的整体分布特征(跨度、宽度、密度)、起始血迹的形态特征(长度、宽度、接触角度)进行分析。结果匕首形成抛甩血迹的分布跨度最小(P0.05);在整体分布宽度上,菜刀最小(P0.05);在整体分布密度上,除菜刀与方锤之间差异无统计学意义,其他工具两两之间差异均有统计学意义(P0.05)。方锤较其他三种工具在起始血迹点长度上最长(P0.05);菜刀与方锤、匕首与方锤在起始血迹点宽度上差异有统计学意义(P0.05)。结论每一类型的打击工具所形成的垂直抛甩血迹形态具有一定的特征,可用于命案现场推断打击工具的类型。     

不同高度滴落血在3种不同载体上的形态和平均直径

暴力犯罪现场一般都会留下各种血迹,如滴落状、喷溅状、流柱状、擦拭状、抛射状血迹等[1,2],能够反映出血迹形成的方式、受害人出血时的位置、出血后的活动情况以及案件发生过程中其它有价值的信息,据此可以重现犯罪现场所发生事件的过程,在甄别证人证言及犯罪嫌疑人供述等方面有非常重要的意义。本文作者将抗凝人血从不同高度垂直滴落在表面光滑程度不等的物体上,对物体上血迹的形态和大小进行测量和观察,旨在找出垂直滴落血迹的特点及形态变化规律,为分析鉴别刑事案件现场的血迹特征提供实验参考资料。1材料与方法将滴管吸满新鲜的抗凝人…     

血迹分析在现场血迹提取中的应用

对命案现场血迹的研究和分析历来是命案现场勘验及现场分析的重要组成部分。传统上,对现场血迹的研究分析侧重于对血迹形态及其形成过程的分析和研究,通过对现场血迹的分布规律及形态特征的观察和测量,判断血迹来源与形成机制,进而推断血迹与案件或犯罪事实之间的关系和过程[1]。     

Deducing drop size and impact velocity from circular bloodstains

An experimental study was done to determine the diameter and velocity of blood drops falling on a surface by measuring the size of bloodstains they produced and counting the number of radial spines projecting from them. Bloodstains were formed by releasing drops of pig blood with a range of diameters (3.0-4.3 mm) and impact velocities (2.4-4.9 m/s), onto four different flat surfaces (glass, steel, plastic, paper) with varying roughness (0.03-2.9 microm). High-speed photography was used to record drop impact dynamics. Bloodstain diameters and the number of spines formed around the rim of stains increased with impact velocity and drop diameter. Increasing surface roughness reduced stain diameter and promoted merging of spines, diminishing their number. Equations are presented that explicitly relate drop diameter and impact velocity to measurements of stain diameter and number of spines.     

Fundamental studies of bloodstain formation and characteristics

A detailed understanding of blood droplet impact dynamics and stain formation is an essential prerequisite to the interpretation of both individual bloodstains and spatter patterns. The current literature on theoretical models for the spreading and splashing of liquid drops on surfaces relevant to the forensic context of bloodstain formation has been reviewed. These models have been evaluated for a paper substrate using experimental data obtained as function of droplet size, impact velocity and angle. It is shown that for perpendicular impact there are fairly simple mathematical models for the spreading diameter and the number of scallops or spines formed around the stain though these have quite limited ranges of validity in their basic form. In particular, predictions for the diameter are best for small droplets impacting at high velocity and the number of spines saturates for higher impact velocities. In the case of spreading, a modification to the energy conservation model is found to provide excellent agreement with experimental stain diameters across a wide range of impact velocities. For non-perpendicular impact, the width of stains is found to depend principally on the normal component of impact velocity and may be predicted by an appropriate modification to the expression for the perpendicular case. Limitations in the calculation of impact angle from the stain aspect ratio are identified and a theoretical basis for the prediction of spines around an elliptical stain is proposed. Some key issues for future research are identified which include a systematic, quantitative study of the effect of surface properties on bloodstain formation.     

Predicting the position of the source of blood stains for angled impacts

Droplets of pig's blood were dropped onto paper at different angles to the horizontal to produce blood stains. Impact velocities varied from 1.82 to 5.76 m/sec, drop size from 3.7 to 5.0 mm in diameter, and the surface sloped at angles between 22.7 degrees and 90 degrees to the horizontal. From the data a single equation relating stain size to drop size and velocity for all impact angles was produced; ab = 111.74 (Re(1/2)We(1/4))(0.75)D(o)D(o) + 0.00084 with R(2) = 0.88, where a is the stain width, b the stain length, Re the Reynolds number, and We the Weber number. A second equation related the number of spines, N, to drop size, velocity, and surface slope for all impact angles as N = 0.76 We(0.5) sin(3)theta with R(2) = 0.9, where theta is the impact angle. Combining these equations the impact velocity can be determined and hence the position of the stain's source.     

Quantitative Differentiation of Bloodstain Patterns Resulting from Gunshot and Blunt Force Impacts

Bloodstain pattern analysis (BPA) provides significant evidentiary value in crime scene interpretation and reconstruction. In this work, we develop a quantitative methodology using digital image analysis techniques to differentiate impact bloodstain patterns. The bloodstain patterns were digitally imaged and analyzed using image analysis algorithms. Our analysis of 72 unique bloodstain patterns, comprising more than 490,000 individual droplet stains, indicates that the mean drop size in a gunshot spatter pattern is at most 30% smaller than the mean drop stain size in blunt instrument patterns. In contrast, we demonstrate that the spatial distribution of the droplet stains—their density as a function of position in the pattern—significantly differs between gunshot and blunt instrument patterns, with densities as much as 400% larger for gunshot impacts. Thus, quantitative metrics involving the spatial distribution of droplet stains within a bloodstain pattern can be useful for objective differentiation between blunt instrument and gunshot bloodstain patterns.     

A blind trial evaluation of a crime scene methodology for deducing impact velocity and droplet size from circular bloodstains

In a previous study, mechanical engineering models were utilized to deduce impact velocity and droplet volume of circular bloodstains by measuring stain diameter and counting spines radiating from their outer edge. A blind trial study was subsequently undertaken to evaluate the accuracy of this technique, using an applied, crime scene methodology. Calculations from bloodstains produced on paper, drywall, and wood were used to derive surface-specific equations to predict 39 unknown mock crime scene bloodstains created over a range of impact velocities (2.2-5.7 m/sec) and droplet volumes (12-45 microL). Strong correlations were found between expected and observed results, with correlation coefficients ranging between 0.83 and 0.99. The 95% confidence limit associated with predictions of impact velocity and droplet volume was calculated for paper (0.28 m/sec, 1.7 microL), drywall (0.37 m/sec, 1.7 microL), and wood (0.65 m/sec, 5.2 microL).     

Preliminary Observations on the Ability of Hyperspectral Imaging to Provide Detection and Visualization of Bloodstain Patterns on Black Fabrics

Abstract: The analysis of bloodstain patterns can assist investigators in understanding the circumstances surrounding a violent crime. Bloodstains are routinely subjected to pattern analysis, which is inherently dependent upon the ability of the examiner to locate and visualize bloodstain patterns on items of evidence. Often, the ability to properly visualize bloodstain patterns is challenging, especially when the stain patterns occur on dark and/or patterned substrates. In this study, preliminary research was performed to better understand how near‐infrared reflectance hyperspectral imaging (HSI) could be used to observe bloodstain patterns on commonly encountered black fabrics. The ability of HSI to visualize latent bloodstains on several commonly encountered substrates is demonstrated. The images acquired through HSI are of sufficient quality to allow for differentiation between stains produced from an impact mechanism or a transfer mechanism. This study also serves as a proof of concept in the differentiation of multiple staining materials. Because of its ability to generate spectral data, the data provide a preliminary separation of stains where more than one type of stain existed.     

Blood droplet dynamics--I

The interpretation of bloodstain patterns at crime scenes has received increased attention in recent years. Important to an understanding of this is knowledge of the fundamentals of blood droplet formation and impact dynamics. A review of the literature reveals that a considerable amount of work has been done with aqueous drop dynamics. Workers in the forensic science area seem to have been unaware of this. In addition, some of the most important and comprehensive early work with blood droplet dynamics seems to have been forgotten. It is not cited in more recent publications dealing with bloodstain pattern interpretation. This literature is reviewed and discussed as well. The present study presents results of experiments with blood droplet dynamics and high-speed photographs of blood droplet impacts on stationary target surfaces. Some longstanding misconceptions of importance to forensic scientists engaged in crime scene reconstruction are discussed.     

玻璃刺创形态学特点的初步研究

目的研究玻璃刺创的形态学特点。方法分别用3个厚度为0．31cm带尖状突起的啤酒瓶残端及3块厚度为0．29cm有尖的普通窗玻璃碎片按设定的不同方向刺击带皮猪肉组织,重复此过程3次,形成198例创口,观察、编号、拍照、测量各创口。结果198例创口的整体形态可分为5种类型,即“工”型、“”型、“”型、“上”型与“一”型,各型在不同刺击方向的分布上存在差异,其中前4种为主要类型,共约占总数的93％,其共同点为在损伤的中部出现了一段与损伤整体走向垂直的创口,啤酒瓶残端所致垂直创口的长度为0．31±0．Olcm（x±s）,窗玻璃碎片所致垂直创口的长度为0．29±0．Olcm（x±s）。结论损伤中部有与损伤整体走向垂直的短创口是玻璃刺创中易出现的一种形态学特点,垂直创的长度与致伤玻璃的厚度具有一致性。     

即刻刺激对中国树鼩体内DA、cAMP、cGMP水平的影响

目的探索即刻刺激对中国树鼩体内DA、cAMP、cGMP水平的影响。方法给予中国树鼩电刺激后,即刻采取血液和组织,用放射免疫法检测多巴胺（DA）、环磷酸腺苷（cAMP）、环磷酸鸟苷（cGMP）的水平。结果电刺激组中国树鼩大脑前额叶皮层（PFC）、海马（Hipp）、纹状体（striatum）、伏隔核（Nac）组织中DA水平比对照组分别升高了52.33%、38.98%、25.25%、45.06%（P〈0.01）;电刺激组中国树鼩血液中c AMP、c GMP水平比对照组分别增加了30.99%、14.94%（P〈0.05,P〈0.01）;c AMP/c GMP比值比对照组增加了18.73%（P〈0.01）;电刺激组中国树鼩中脑腹侧背盖区（VTA）、大脑前额叶皮层（PFC）、海马（Hipp）、睾丸（Testicle）组织中c AMP水平比对照组分别升高了21.84%、24.55%、21.07%、44.87%（P〈0.01）,c GMP水平比对照组分别升高了17.95%、25.57%、35.33%、22.87%（P〈0.05,P〈0.01）。结论即刻刺激能促进中国树鼩体内DA、c AMP、c GMP的合成和释放。     

Passive Drip Stain Formation Dynamics of Blood onto Hard Surfaces and Comparison with Simple Fluids for Blood Substitute Development and Assessment,

The spreading dynamics of blood dripping onto hard surfaces is compared to two spreading models. Samples of human blood, porcine blood, and Millipore^® water were dripped onto cardboard, foamcore, and glass surfaces in low velocity passive drip simulations. Final stain diameter, the total number of spines and scallops, and angle of impact were measured and analyzed. Spreading is best predicted by applying the concept of effective viscosity to the Scheller and Bousfield (R² = 0.91) and Roisman (R² = 0.89) spreading models. In the tested conditions, blood spreads with Newtonian tendencies; however, has quantifiable differences in stain appearance to Newtonian fluids like water. This is encouraging for the development of water‐based fluids as synthetic blood substitutes (SBSs). The work presents an assessment platform to quantify and score the performance of simple water‐based fluids using final stain diameter (6 points) and number of spines and scallops (6 points) at six dripping heights between 20 and 120 cm. The angle of impact of a stain alone is not a sensitive measure of SBS performance, but stain formation scores the SBS's performance with another 1 point. Together these features generate a quantitative relative ranking system, of a maximum possible 13 points, that can be used to support the use of a particular fluid for the creation of a drip stain. The performance of twenty simple fluids in the simulated dripping assessment test is described.