5 research outputs found
Application of 3D scanning technology in forensic investigation of bite-marks
No full textForensic investigation of bite-marks on humans has the potential to provide evidence that can be used to identify the perpetrator of a bite. Bite-mark evidence has been used in legal proceedings since 1692 but, recently, bite-mark analysis has been subject to substantial criticism. In the USA, there have now been 24 cases involving human perpetrators in which convictions based on bite-mark analysis have been overturned as a result of DNA evidence, including cases in which the defence experts had testified that the suspect dentitions did not match the bite-marks. The overturn of these convictions and the criticisms that followed have led to calls to halt the use of bite-marks as evidence until its scientific credibility can be established, and even to recommendations to discontinue altogether the use of bite-mark evidence in criminal investigations in the US. To address the fundamental limitations of bite-mark analysis, the aims of this thesis were to estimate the frequency of occurrence of bites, propose the use of 3D imaging technology as an approach to overcome limitations of current methods of bite-mark analysis, investigate the reliability and validity of measurements of landmark dental features made using 3D imaging, and examine the accuracy of matching 3D images of bite-marks to 3D images of candidate dentitions. This thesis is made up of four key studies. They are summarized below: Study 1 An important first step was to undertake an assessment of the public health implications of bites inflicted on humans by estimating the frequency of occurrence of the injuries and deaths caused. For information on bites perpetrated by humans on humans, searches and data requests were made on public access information websites and of the Australian Institute of Health and Welfare (AIHW) respectively. The AIHW was unable to provide age and sex specific information on bites caused by humans on other humans. The author's investigations revealed that there is incomplete and fragmented information on bites perpetrated by humans on humans most commonly in cases of sexual assault and child abuse. Instead the author turned their attention to bites perpetrated by other biting animals, and specifically by dogs because dog-bites are the most common. To determine the extent of the problem, the incidence of public sector hospitalizations resulting from dog-bite related injuries in Australia during the period 2001-2013 was estimated. The principal finding was that on average, 2061 persons were hospitalized each year during that period for treatment for dog-bite injuries at an annual rate of 12.39 (95% CI 12.25, 12.53) per 100,000. The highest annual rates of 25.95 (95% CI 25.16, 26.72) and 18.42 (95% CI 17.75, 19.07) per 100,000 were for age groups 0-4 years and 5-9 years respectively. Rates of recorded events increased over the study period and reached 16.15 (95% CI 15.78, 16.52) per 100,000 during 2011-13. This study was the first national study to report the incidence of hospitalization for injuries due to dog-bites for an extended period with complete coverage of all public hospitals in Australian states and territories. The findings add considerably to what is known about the public health problem of dog-bite injuries in Australia. Study 2 Recently, the scientific basis of bite-mark analysis has been questioned. The most robust of those criticisms came from the National Academy of Science (NAS). In its report published in 2009, the NAS identified three fundamental limitations of bite-mark analysis. These were that the uniqueness of human dentitions was yet to be determined, that the ability of the human skin to retain faithfully the impression of the biting dentition was yet to be ascertained, and that comprehensive steps to minimise and quantify all other sources of error in matching a bite-mark to a suspect dentition were yet to be undertaken. To address these fundamental limitations, the author recommends the use of 3D imaging techniques in bite-mark analysis. The new generation of portable, non-invasive, hand-held intra-oral 3D scanners, that are currently used as an alternative to conventional dental impression materials in clinical dentistry, have made the process of acquiring dental impressions faster and easier. The 3D scanning permits the imaging of bite-marks as well as the imaging of biting dentitions of suspected perpetrators in 3 dimensions with high resolution, and would allow researchers to compile large databases of virtual images of dentitions of biting animals for quantifying population variation. In addition, 3D scanning would make it feasible to compare a large number of landmark features when matching the scan of a bite-mark to the scan of a candidate dentition. This technology makes it possible to investigate the sources of error and quantify that error, and thereby has the potential to remove or at least reduce error including by limiting subjectivity associated with human judgement. Study 3 To investigate the reliability and validity of measurements made with an intra-oral 3D scanner, two raters each measured 84 tooth and 26 arch features of 50 sets of upper and lower human dental casts first using digital hand-held callipers and second using the measuring tool provided with the ZFX IntraScan intra-oral 3D scanner applied to 3D images of the dental casts. The measurements were repeated at least one week later. Reliability and validity were quantified concurrently by calculation of intra-class correlation coefficients (ICC) and standard errors of measurement (SEM). The measurements of 110 landmark features of human dental casts made using the intra-oral 3D scanner were virtually indistinguishable from measurements of the same features made using conventional hand-held callipers. The difference of means as a percentage of the average of the measurements by each method ranged between 0.030% and 1.134%. The inter-method SEMs ranged between 0.037% and 0.535%, and the inter-method ICCs ranged between 0.904 and 0.999, for both the upper and the lower arches. The inter-rater SEMs were one-half, and the intra-method/rater SEMs were one-third, of the inter-method values. This study demonstrated that the ZFX Intrascan intra-oral 3D scanner with its virtual on-screen measuring tool is a reliable and valid method for measuring the key features of human dental casts. Study 4 The aim of study 4 was to assess the accuracy of matching 3D images of 3D impressions of dental arches with 3D images of candidate dentitions. In this proof-of-concept study, dog dental arches were used as a model because demonstration of success in matching to dentitions with substantial variation due to inter-breed differences between dogs was a logical starting point. A further consideration was that there was greater access to dog dentitions than to human dentitions. 3D images of dog dental arches and their impressions were recorded using the intra-oral 3D scanner A single rater measured and re-measured 79 landmark dental features on each of the 3D images of 40 upper and the lower dog dental arches (positive images) using the virtual onscreen measuring tool provided with the intra-oral 3D scanner. This was repeated for 3D images of the impressions of dog dental arches in modelling clay (negative images). Measurements extracted from the images were used in an attempt to match the negative images to positive images. The measurements of 79 landmark features of the dog dental arches were nearly identical to measurements of the same features made on the impressions of dog dental arches on clay. The intra-rater intra-class correlation coefficients (ICCs) were greater than 0.937, and the intra-rater SEMs ranged between 0.041 and 0.076 for both the upper and the lower arches. Using the measurements of all 79 features, or even just those of anterior dentition, there was a 100% accuracy in matching the negative images to positive images of the dentitions. Nevertheless, some features contributed to the overall match rate more than the others. This study demonstrates that the portable intra-oral 3D scanner can record impressions of dental features with sufficient accuracy to allow identification of the dog-dentition that caused an undistorted bite-mark. In conclusion, bite-mark evidence has the potential to provide supporting evidence to build a case against the human or animal perpetrator of a bite. Even when DNA evidence is available, and that is always not the case, supporting evidence from finger-prints and bite-marks helps to build a more compelling case. However, for bite-mark evidence to have probative value, it is necessary to address scientific criticisms of the methods used in obtaining it. In this thesis,this author proposes the use of intra-oral 3D scanning principally because of its potential for limiting and quantifying error. The reliability and validity of measurements of human dentitions has been established and a proof-of-concept of the accuracy of matching bite-marks with dentitions has been provided. A framework for future research is proposed, with recommendations for addressing the other limitations of bite-mark analysis. Specifically, the author proposes the establishment of databases of scanned images of dentitions of biting animals and map a path forward in the investigation of distortion in bite-marks
Flexible, large-area, multi-layered graphene/cellulose composite for dye filtration applications
No full textTextile and clothing industry effluents are the primary source of water pollution, affecting aquatic animals and plants. The need of the hour is to filter these effluents to avoid contamination. Nanofiltration using carbon-based membranes is an effective method in dye filtration. The present work describes graphene oxide (GO) and reduced graphene oxide (RGO) coated cellulose surfaces for dye filtration. These sheets exhibited high porosity, large surface area, high flexibility, inexpensive, easy to fabricate, and successfully employed for efficient nano dye filtration. The novelty of the present work is the filtration of most industrially used dyes such as methylene blue and rose bengal. Results confirm the filtration up to 98% and 94% for both Methylene Blue (MB) and Rose Bengal (RB) dyes, respectively, and the eco-friendly mode of treating industrial dye-contaminated water.The author S.M. thanks VGST, Govt of Karnataka for the financial support under SMYSR Programme [Ref Letter No: No/VGST/GRD-585/2016-17/2017-18/39 dated 19–04-2018] and Siddaganga Institute of Technology, Tumakuru for the financial support. The authors thank Mr. Rajshekar Pujar for scientific discussions, and NNM thanks the Karnataka Council for Technological Upgradation, Govt of Karnataka. (KCTU/R&D/SIT-Nano/2016-17/399)
Wound healing activity of aqueous extract of Crotalaria verrucosa in Wistar albino rats
No full textAbstractObjectiveTo evaluate the wound healing effect of aqueous extract of Crotalaria verrucosa (C. verrucosa) in rats.MethodsThree wound models including incision, excision and dead space wounds were used in this study. The parameters studied were breaking strength in incision models, granulation tissue dry weight, breaking strength and hydroxyproline content in dead space wounds, percentage of wound contraction and period of epithelialization in excision wound model.ResultsTwo doses of the extract with and without dexamethasone showed significant increases in mean hydroxyproline, total protein content and dry weight of granulation tissue but it was higher with dose 800 mg/kg comparing with the control. The dexamethasone treated group showed a significant (P<0.001) reduction in the wound breaking strength when compared to control group in incision type of wound model. Coadministration of C. verrucosa with dexamethasone significantly (P<0.001) increased the breaking strength compared to the dexamethasone treated only group. In excision wound model, the percentage of the wound contraction was significantly (P<0.01) increased by two doses of test extract on all the days except the lower dose which exhibited only on 12 th, 16 th days of drug treatment and it also reversed the dexamethasone suppressed wound contraction. It significantly (P <0.001) reduced the time required for epithelialization and reversed the epithelialization delaying effect of dexamethasone (P<0.001).ConclusionsC. verrucosa was found to possess significant wound healing property. This was evident by decrease in the period of epithelialization, increase in the rate of wound contraction, skin breaking strength, and granulation tissue dry weight content. Hence C. verrucosa could be a good wound healing agent
Isothermal Flow Field Characterization of a Full-Scale Sector Combustor At Elevated Pressures
No full textAn experimental investigation in a sector (20 degree) of full-scale annular gas turbine combustor is performed. The distinctive feature of the experimental setup is that it preserves the geometrical details of an annular combustor that includes the casing, dome and combustor liner. The combustor design features a series of primary and secondary dilution holes with multiple film cooling strips on the outer and inner liner. In the present study, the combustor is operated at inlet Mach numbers of 0.02 - 0.3 at operating absolute pressures of 1 - 5 bar. Static pressure measurements are performed at multiple locations in the rig to characterize the pressure drop across the combustor. Two-dimensional particle image velocimetry (PIV) is performed to measure the velocity fields of the primary and exit zones of the combustor simultaneously. The results show the presence of a central recirculation zone (CRZ), high-velocity annular jets, and a pair of dilution jets in the primary zone of the combustor. The steady-state flow structures are invariant of inlet Mach number and pressures. The relationship between the relative pressure drop across the combustor and the combustor inlet condition is obtained. Mass flow rate and momentum flux are calculated for the flow through the swirl cup, central recirculation zone, the primary dilution jets, and the exit zone. The paper shows how the flow structures in a realistic combustor change with variations in global combustor parameters.The authors thank the Gas Turbine Research Establishment (GTRE) and Centre of Propulsion Technology (CoPT) for financial support of the research. The authors thank GTRE for its support in rig development and manufacturing. Author Darshan Rathod thanks the Prime Minister Research Fellowship (PMRF) for providing the research opportunity and scholarship. The measurements were performed using the facility of the National Center for Combustion Research and Development (NCCRD), ICER, IISc, Bangalore. The authors extend their thanks to Mr. Harsha Rajshekar and Ms. Samprada Kumbhare for their assistance in the experiment
