1,721,003 research outputs found
A comparsi between four different methods of sampling GSR from gunshot wounds in skin and bone: different applicability and reliability
No full textBackground and Aims: the sampling procedures of gunshot residues (GSR) on entry wounds is crucial and still a precise agreement on sampling procedures is yet lacking. Thus, an experimental study on GSR sampling was performed.
Materials and Methods: a total of 20 samples (ten of pig skin free of fur and ten of bovine ribs without soft tissues) were shot once at a firing ground, with a semiautomatic pistol with 9x21 mm projectiles (full-metal-jacketed bullets). Moreover, two unshot samples (one pig skin and one bovine rib) were kept as controls. Samples were fired with a near-contact range and a range of about 40 cm, keeping the muzzle perpendicular to the surface of the sample. The periphery of the wound was divided into 4 wedges and collection of GSR was performed with graphite tape, white canvas tape, transparent adhesive tape and cotton swabs soaked in alcohol, one for each centimeter from the wound edges, up to a distance of 3 cm. The same samplings were performed on controls. Samples were treated with 1 ml 30% ultrapure nitric acid, diluted to 10 ml with MilliQ water, filtered with 0.45 micron Nylon filter and each sample was analyzed with ICP-OES (for Ba, Pb), ICP-MS (more sensitive for Sb, Pb, Cu) and GC-MS (for organic elements, usually present along with inorganic elements: i.e. ethyl centralite, phthalates), after the samples were treated with isopropyl alcohol (1 ml) and diluted to 5 ml with acetone. Moreover, two samples of shot bovine ribs (one with near-contact range, one with distant range) were also analyzed by SEM-EDX to identify GSR by drying the sample in vacuo.
Results: First results showed the stub method with cotton swabs as best sampling procedure, since this technique enabled the highest amounts of residues to be gathered, and blank samplings showed higher purity with less interference by contaminants; the highest amount of metals were detected within the first 2-3 cm around the wound with near-contact ranges, while according to the results provided by the direct analysis with SEM in dried samples, constant concentration within 3-4-5 cm were detected with distant range. In all cases, stub and bones did not interfere with the element determination, as showed by blanks proofs. The determination of the element ratio (Cu/Pb, Sb/Pb) in most cases provided more reliable results and should thus be considered a better choice than the determination of single elements, since contaminations were evidenced and the elements' ratio in the bullets are quiet constant. The complementary combination of the methods used (ICP-OES, ICP-MS and GC-MS) provided an accurate assessment of the type of residues and concentrations, even though ICP-MS showed the highest sensitivity in the detection of inorganic metallic residues than ICP-OES.
Conclusions: The study shows the importance of the sampling procedures in case of gunshot wounds: from a quali-quantitative point of view, cotton swabs appeared to be the best sampling procedure, and the combination between ICP-MS and GC-MS provided a reliable assessment of the type, amounts and distribution of GSR
The Influence of Alkaline or Acid Liquids on Cut Marks and on the Structure of Bone: An Experimental Study on Porcine Ribs
No full textAfter attending this presentation, attendees will be aware of the macroscopic and microscopic effects of acid and basic solutions
when used with the purpose of destroying a corpse and thus hindering discovery and identification.
This presentation will impact the forensic science community by highlighting the effects of acid and basic solutions on bone and the
importance in correctly assessing their effectiveness in the destruction of tissues and in the modification of signs of trauma.
Among the different methods that are seldom used with the goal of destroying a corpse and thus preventing discovery or at least
identification, the use of highly acidic or basic solutions is something forensic pathologists sometimes have to deal with, especially in
criminal scenarios. Moreover, determining whether a bone (or even a single fragment) was in contact with an acidic/basic solution
could be a crucial question posed to the anthropologist. Of all taphonomical modifications during decomposition processes, little is
known about the action of high or low pH to human tissues and bones. The main question is, are these solutions able to make a cadaver
completely “disappear” and, when human tissues come in contact with these substances, what kind of changes do they undergo? How
are they recognizable? Only a few studies have focused on this issue and have referred only to macroscopic surveys.
In this study, a total of 60 samples of porcine bone (Sus scrofa) were completely skeletonized manually, without any chemical or
other artificial treatment. Furthermore, on each sample, a cut mark was produced with a scalpel in order to evaluate the modifications
that these signs can undergo in such conditions. Specimens were then divided in groups of ten each and put in six different liquid
solutions with different pH (1, 3, 5, 9, 12, 14) prepared by adding sulfuric and acetic acids and sodium hydroxide to water. A neutral
control solution (pH 7) was also prepared.
Specimens were analyzed every five days over a period of 70 days. The appearance of the outer cortical layer of the bone and the
aspect of the cut marks were investigated first macroscopically and then microscopically with a Wild Heerbrug® M650 stereomicroscope
and Scanning Electron Microscopy (SEM). Finally, thin undecalcified sections were prepared and analyzed with a transmitted light
microscope in order to evaluate the changes of the osteonic structures and the appearance of characteristic patterns.
Regarding the macroscopic observation, minimal lytic modifications became evident in all the samples, but only those exposed to a
pH 14 for a long time showed evident alterations of the cortical bone, such as large erosions and cracking. Cut marks showed alterations
in 50% of the cases, especially when exposed to basic solutions, detectable as enlargements, distortions, or detachment of bone flakes.
The most interesting results arose from light microscopy of thin sections: if further significant elements were not gained with
stereomicroscopy, scanning electron microscopy and light microscopy provided the most interesting results. The first enabled the
observation of significant alterations on the surface of the cortical bone, with evident deposits of organic and inorganic matter as the pH
became more acidic and as contact time increased. This layer of matter gives an important contribution to the macroscopic alterations
of cut marks on bone which may, as in the case of pH 1 and 14, no longer be even recognizable.
Moreover, the study showed for the first time that, even without detectable macroscopic alterations, the osteon structure visible in
light microscopy is severely deteriorated by acids and bases, frequently with peculiar patterns, like radial or multidirectional cracking.
The information gained from the present study can be of great help in the detection of an exposure of human tissues to high or low
environmental pH and in understanding the effects that these solutions can exert on human bones. Extreme pH can significantly alter
the structure of human bone and make signs of traumas undetectable, but the contact between solutions and bone can be detected if
thoroughly analyzed, especially through light microscopy
Dismemberment and Toolmark Analysis on Bone: A Microscopic Analysis of the Walls of Cut Marks
No full textForensic anthropology may be fundamental in gaining important investigative information in cases of dismemberment: a thorough anthropological survey including the micro- and macromorphological and metrical analysis of marks/lesions found in bones and the microscopic search of residues within the lesions can play a crucial role in providing answers to questions often related to causes and modalities of death as well as to dismemberment tools and methods used. In dismemberment cases, in fact, one of the main objectives is to identify sharp tool classes used in the dismemberment and eventually correlate one specific presumed tool with specific cut marks found in bones. But sometimes additional information may be required as described in the case presented here, for which there has been the need to set up a judicial experiment whose results highlighted again the many lacunae still existing in this field and the need to expand research on toolmark analysi
A Comparative Analysis of Macroscopic, Microscopic, and Chemical Alterations in Modern and Ancient Bones: A Preliminary Study
Full text linkThe survival of metallic residues from gunshot wounds in cremated bone : a SEM-EDX study
No full textThe research and analysis of gunshot residues has a relevant role in the examination of gunshot wounds. Nevertheless, very little literature exists concerning gunshot wounds on charred material. In this study, 16 adult bovine ribs (eight still with soft tissues and eight totally skeletonized) underwent a shooting test with two types of projectiles (9 mm full metal-jacketed bullet and 9 mm unjacketed bullet). Each rib then underwent a charring process in an electric oven, reaching the stage of complete calcination at 800°C. The area of each entrance wound was analyzed before and after the carbonization process via a scanning electron microscope (SEM) equipped with an energy dispersive X-ray analyzer (EDX). In each sample, metallic residues composed of lead, barium, and antimony were found. These metallic residues were thus preserved also after exposure to the extremely high temperatures reached within the oven, especially with unjacketed bullets, although the particles seem to be more irregular in shape as a result of the heating process. In conclusion, this study proved that gunshot residues survive extremely high temperatures and can be detected via SEM/EDX even in cases of charred tissues
SEM-EDS analysis on the skin of cadavers for the detection of environmental residues: a valuable help to forensic investigations
No full textBackground and aims: in recent years the field of application of forensic disciplines has broadened with the assistance provided by other scientific disciplines such as biochemistry, botany, entomology. A clear example is the use of SEM-EDS (scanning electron microscope with an energy dispersive X-ray spectrometry) which can provide a magnification of microscopic structures and a chemical analysis of residues. It is now widely used to identify of the wounding weapon in cases of blunt, sharp force and gunshot wounds but its importance may also include the search for environmental residues. However, a thorough investigation considering the impact of SEM-EDS analysis of skin of cadavers for the assessment of environmental residues, has never been performed.
Materials and methods: the assessment of environmental residues was performed on the skin of a total of 27 corpses subjected to autopsy in the Institute of Legal Medicine of Milan, recovered in different environments and in two different seasons, aged between 20 and 94 years and died for natural or traumatic causes. The experimental project first aimed at verifying possible differences in residues between covered and uncovered areas: four samples were taken from two covered areas (anterior part of the chest and back) and two from uncovered areas (hand dorsal surface and forehead) by means of a circular adhesive tape of graphite (diameter 1cm).
Skin samples were coated with graphite and analyzed by Cambridge Stereoscan 360 and EDS spectrometry. Fragments of adhesive tape, not applied to the skin surface, were used as negative controls. Moreover, as further control, samples were performed in the environments where corpses were discovered.
Results: a wide variability of residues can be detected on skin, sometimes related to specific events (i.e. residues of vehicles and brakes in case of car accidents): concerning single elements, covered areas showed in average less amounts of particles than the uncovered ones, especially for what concerns iron, calcium, sodium, magnesium, chrome; differences were statistically significant (p<0.05).
Conclusions: Differences between samples performed on covered and uncovered skin areas confirm the tight link between body and environment. The characterization of the residues on the skin may provide useful information for the reconstruction of the events: the study highlights the importance of an environmental point of view among the practice of forensic pathology
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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